diff --git a/include/net/lwm2m.h b/include/net/lwm2m.h
index f5c944c2686..6b0df37663e 100644
--- a/include/net/lwm2m.h
+++ b/include/net/lwm2m.h
@@ -123,10 +123,10 @@ int lwm2m_device_add_err(u8_t error_code);
 #define RESULT_UNSUP_PROTO	9
 
 #if defined(CONFIG_LWM2M_FIRMWARE_UPDATE_OBJ_SUPPORT)
-#if defined(CONFIG_LWM2M_FIRMWARE_UPDATE_PULL_SUPPORT)
 void lwm2m_firmware_set_write_cb(lwm2m_engine_set_data_cb_t cb);
 lwm2m_engine_set_data_cb_t lwm2m_firmware_get_write_cb(void);
 
+#if defined(CONFIG_LWM2M_FIRMWARE_UPDATE_PULL_SUPPORT)
 void lwm2m_firmware_set_update_cb(lwm2m_engine_exec_cb_t cb);
 lwm2m_engine_exec_cb_t lwm2m_firmware_get_update_cb(void);
 #endif
diff --git a/samples/net/lwm2m_client/src/lwm2m-client.c b/samples/net/lwm2m_client/src/lwm2m-client.c
index 6ffbcc57c28..347bb667a49 100644
--- a/samples/net/lwm2m_client/src/lwm2m-client.c
+++ b/samples/net/lwm2m_client/src/lwm2m-client.c
@@ -147,6 +147,7 @@ static int device_factory_default_cb(u16_t obj_inst_id)
 	return 1;
 }
 
+#if defined(CONFIG_LWM2M_FIRMWARE_UPDATE_PULL_SUPPORT)
 static int firmware_update_cb(u16_t obj_inst_id)
 {
 	SYS_LOG_DBG("UPDATE");
@@ -160,7 +161,9 @@ static int firmware_update_cb(u16_t obj_inst_id)
 	lwm2m_engine_set_u8("5/0/5", RESULT_SUCCESS);
 	return 1;
 }
+#endif
 
+#if defined(CONFIG_LWM2M_FIRMWARE_UPDATE_OBJ_SUPPORT)
 static int firmware_block_received_cb(u16_t obj_inst_id,
 				      u8_t *data, u16_t data_len,
 				      bool last_block, size_t total_size)
@@ -169,6 +172,7 @@ static int firmware_block_received_cb(u16_t obj_inst_id,
 		    data_len, last_block);
 	return 1;
 }
+#endif
 
 static int lwm2m_setup(void)
 {
@@ -212,10 +216,12 @@ static int lwm2m_setup(void)
 
 	/* setup FIRMWARE object */
 
-	lwm2m_engine_register_post_write_callback("5/0/0",
-						  firmware_block_received_cb);
+#if defined(CONFIG_LWM2M_FIRMWARE_UPDATE_OBJ_SUPPORT)
 	lwm2m_firmware_set_write_cb(firmware_block_received_cb);
+#endif
+#if defined(CONFIG_LWM2M_FIRMWARE_UPDATE_PULL_SUPPORT)
 	lwm2m_firmware_set_update_cb(firmware_update_cb);
+#endif
 
 	/* setup TEMP SENSOR object */
 
diff --git a/subsys/net/lib/lwm2m/Kconfig b/subsys/net/lib/lwm2m/Kconfig
index 6be9348a207..d86a95e5f3d 100644
--- a/subsys/net/lib/lwm2m/Kconfig
+++ b/subsys/net/lib/lwm2m/Kconfig
@@ -137,17 +137,23 @@ config LWM2M_FIRMWARE_UPDATE_PULL_SUPPORT
 	  block transfer and "FIRMWARE PACKAGE URI" resource.  This option
 	  adds another UDP context and packet handling.
 
-config LWM2M_FIRMWARE_UPDATE_PULL_COAP_BLOCK_SIZE
-	int "Firmware Update object pull CoAP block size"
-	depends on LWM2M_FIRMWARE_UPDATE_PULL_SUPPORT
+config LWM2M_COAP_BLOCK_SIZE
+	int "LWM2M CoAP block-wise transfer size"
 	default 256
 	default 64 if NET_L2_BT
 	default 64 if NET_L2_IEEE802154
 	range 16 1024
 	help
-	  CoAP block size used by firmware pull when performing block-wise
+	  CoAP block size used by LWM2M when performing block-wise
 	  transfers. Possible values: 16, 32, 64, 128, 256, 512 and 1024.
 
+config LWM2M_NUM_BLOCK1_CONTEXT
+	int "Maximum # of LWM2M block1 contexts"
+	default 3
+	help
+	  This value sets up the maximum number of block1 contexts for
+	  CoAP block-wise transfer we can handle at the same time.
+
 config LWM2M_RW_JSON_SUPPORT
 	bool "support for JSON writer"
 	default y
diff --git a/subsys/net/lib/lwm2m/lwm2m_engine.c b/subsys/net/lib/lwm2m/lwm2m_engine.c
index 7d014d1568a..bde50bde953 100644
--- a/subsys/net/lib/lwm2m/lwm2m_engine.c
+++ b/subsys/net/lib/lwm2m/lwm2m_engine.c
@@ -16,8 +16,6 @@
  *
  * - Use server / security object instance 0 for initial connection
  * - Add DNS support for security uri parsing
- * - Block-transfer support / Large response messages
- *   (use Block2 to limit message size to 64 bytes for 6LOWPAN compat.)
  * - BOOTSTRAP/DTLS cleanup
  * - Handle WRITE_ATTRIBUTES (pmin=10&pmax=60)
  * - Handle Resource ObjLink type
@@ -102,6 +100,24 @@ static sys_slist_t engine_obj_list;
 static sys_slist_t engine_obj_inst_list;
 static sys_slist_t engine_observer_list;
 
+#define NUM_BLOCK1_CONTEXT	CONFIG_LWM2M_NUM_BLOCK1_CONTEXT
+
+/* TODO: figure out what's correct value */
+#define TIMEOUT_BLOCKWISE_TRANSFER K_SECONDS(30)
+
+#define GET_BLOCK_NUM(v)	((v) >> 4)
+#define GET_BLOCK_SIZE(v)	(((v) & 0x7))
+#define GET_MORE(v)		(!!((v) & 0x08))
+
+struct block_context {
+	struct zoap_block_context ctx;
+	s64_t timestamp;
+	u8_t token[8];
+	u8_t tkl;
+};
+
+static struct block_context block1_contexts[NUM_BLOCK1_CONTEXT];
+
 /* periodic / notify / observe handling stack */
 static K_THREAD_STACK_DEFINE(engine_thread_stack,
 			     CONFIG_LWM2M_ENGINE_STACK_SIZE);
@@ -160,6 +176,101 @@ static char *sprint_token(const u8_t *token, u8_t tkl)
 }
 #endif
 
+/* block-wise transfer functions */
+
+enum zoap_block_size lwm2m_default_block_size(void)
+{
+	switch (CONFIG_LWM2M_COAP_BLOCK_SIZE) {
+	case 16:
+		return ZOAP_BLOCK_16;
+	case 32:
+		return ZOAP_BLOCK_32;
+	case 64:
+		return ZOAP_BLOCK_64;
+	case 128:
+		return ZOAP_BLOCK_128;
+	case 256:
+		return ZOAP_BLOCK_256;
+	case 512:
+		return ZOAP_BLOCK_512;
+	case 1024:
+		return ZOAP_BLOCK_1024;
+	}
+
+	return ZOAP_BLOCK_256;
+}
+
+static int
+init_block_ctx(const u8_t *token, u8_t tkl, struct block_context **ctx)
+{
+	int i;
+	s64_t timestamp;
+
+	*ctx = NULL;
+	timestamp = k_uptime_get();
+	for (i = 0; i < NUM_BLOCK1_CONTEXT; i++) {
+		if (block1_contexts[i].tkl == 0) {
+			*ctx = &block1_contexts[i];
+			break;
+		}
+
+		if (timestamp - block1_contexts[i].timestamp >
+		    TIMEOUT_BLOCKWISE_TRANSFER) {
+			*ctx = &block1_contexts[i];
+			/* TODO: notify application for block
+			 * transfer timeout
+			 */
+			break;
+		}
+	}
+
+	if (*ctx == NULL) {
+		SYS_LOG_ERR("Cannot find free block context");
+		return -ENOMEM;
+	}
+
+	(*ctx)->tkl = tkl;
+	memcpy((*ctx)->token, token, tkl);
+	zoap_block_transfer_init(&(*ctx)->ctx, lwm2m_default_block_size(), 0);
+	(*ctx)->timestamp = timestamp;
+
+	return 0;
+}
+
+static int
+get_block_ctx(const u8_t *token, u8_t tkl, struct block_context **ctx)
+{
+	int i;
+
+	*ctx = NULL;
+
+	for (i = 0; i < NUM_BLOCK1_CONTEXT; i++) {
+		if (block1_contexts[i].tkl == tkl &&
+		    memcmp(token, block1_contexts[i].token, tkl) == 0) {
+			*ctx = &block1_contexts[i];
+			/* refresh timestmap */
+			(*ctx)->timestamp = k_uptime_get();
+			break;
+		}
+	}
+
+	if (*ctx == NULL) {
+		SYS_LOG_ERR("Cannot find block context");
+		return -ENOENT;
+	}
+
+	return 0;
+}
+
+static void free_block_ctx(struct block_context *ctx)
+{
+	if (ctx == NULL) {
+		return;
+	}
+
+	ctx->tkl = 0;
+}
+
 /* observer functions */
 
 int lwm2m_notify_observer(u16_t obj_id, u16_t obj_inst_id, u16_t res_id)
@@ -530,6 +641,20 @@ int lwm2m_delete_obj_inst(u16_t obj_id, u16_t obj_inst_id)
 
 /* utility functions */
 
+static int get_option_int(const struct zoap_packet *zpkt, u8_t opt)
+{
+	struct zoap_option option = {};
+	u16_t count = 1;
+	int r;
+
+	r = zoap_find_options(zpkt, opt, &option, count);
+	if (r <= 0) {
+		return -ENOENT;
+	}
+
+	return zoap_option_value_to_int(&option);
+}
+
 static void engine_clear_context(struct lwm2m_engine_context *context)
 {
 	if (context->in) {
@@ -1698,6 +1823,12 @@ int lwm2m_write_handler(struct lwm2m_engine_obj_inst *obj_inst,
 	void *data_ptr = NULL;
 	size_t data_len = 0;
 	size_t len = 0;
+	size_t total_size = 0;
+	int ret = 0;
+	u8_t tkl = 0;
+	const u8_t *token;
+	bool last_block = true;
+	struct block_context *block_ctx = NULL;
 
 	if (!obj_inst || !res || !obj_field || !context) {
 		return -EINVAL;
@@ -1719,8 +1850,6 @@ int lwm2m_write_handler(struct lwm2m_engine_obj_inst *obj_inst,
 		data_ptr = res->pre_write_cb(obj_inst->obj_inst_id, &data_len);
 	}
 
-	/* TODO: check for block transfer fields here */
-
 	if (data_ptr && data_len > 0) {
 		switch (obj_field->data_type) {
 
@@ -1808,14 +1937,30 @@ int lwm2m_write_handler(struct lwm2m_engine_obj_inst *obj_inst,
 	}
 
 	if (res->post_write_cb) {
+		/* Get block1 option for checking MORE block flag */
+		ret = get_option_int(in->in_zpkt, ZOAP_OPTION_BLOCK1);
+		if (ret >= 0) {
+			last_block = !GET_MORE(ret);
+
+			/* Get block_ctx for total_size (might be zero) */
+			token = zoap_header_get_token(in->in_zpkt, &tkl);
+			if (token != NULL &&
+			    !get_block_ctx(token, tkl, &block_ctx)) {
+				total_size = block_ctx->ctx.total_size;
+			}
+		}
+
 		/* ignore return value here */
-		res->post_write_cb(obj_inst->obj_inst_id, data_ptr, len,
-				   false, 0);
+		ret = res->post_write_cb(obj_inst->obj_inst_id, data_ptr, len,
+					 last_block, total_size);
+		if (ret >= 0) {
+			ret = 0;
+		}
 	}
 
 	NOTIFY_OBSERVER_PATH(path);
 
-	return 0;
+	return ret;
 }
 
 static int lwm2m_write_attr_handler(struct lwm2m_engine_obj *obj,
@@ -2103,20 +2248,6 @@ static int do_write_op(struct lwm2m_engine_obj *obj,
 	}
 }
 
-static int get_observe_option(const struct zoap_packet *zpkt)
-{
-	struct zoap_option option = {};
-	u16_t count = 1;
-	int r;
-
-	r = zoap_find_options(zpkt, ZOAP_OPTION_OBSERVE, &option, count);
-	if (r <= 0) {
-		return -ENOENT;
-	}
-
-	return zoap_option_value_to_int(&option);
-}
-
 static int handle_request(struct zoap_packet *request,
 			  struct lwm2m_message *msg)
 {
@@ -2133,6 +2264,9 @@ static int handle_request(struct zoap_packet *request,
 	struct lwm2m_engine_context context;
 	int observe = -1; /* default to -1, 0 = ENABLE, 1 = DISABLE */
 	bool discover = false;
+	struct block_context *block_ctx = NULL;
+	size_t block_offset = 0;
+	enum zoap_block_size block_size;
 
 	/* setup engine context */
 	memset(&context, 0, sizeof(struct lwm2m_engine_context));
@@ -2208,7 +2342,7 @@ static int handle_request(struct zoap_packet *request,
 			context.operation = LWM2M_OP_READ;
 		}
 		/* check for observe */
-		observe = get_observe_option(in.in_zpkt);
+		observe = get_option_int(in.in_zpkt, ZOAP_OPTION_OBSERVE);
 		zoap_header_set_code(out.out_zpkt, ZOAP_RESPONSE_CODE_CONTENT);
 		break;
 
@@ -2245,7 +2379,31 @@ static int handle_request(struct zoap_packet *request,
 	in.inpos = 0;
 	in.inbuf = zoap_packet_get_payload(in.in_zpkt, &in.insize);
 
-	/* TODO: check for block transfer? */
+	/* Check for block transfer */
+	r = get_option_int(in.in_zpkt, ZOAP_OPTION_BLOCK1);
+	if (r > 0) {
+		/* RFC7252: 4.6. Message Size */
+		block_size = GET_BLOCK_SIZE(r);
+		if (GET_MORE(r) &&
+		    zoap_block_size_to_bytes(block_size) > in.insize) {
+			SYS_LOG_DBG("Trailing payload is discarded!");
+			r = -EFBIG;
+			goto error;
+		}
+
+		if (GET_BLOCK_NUM(r) == 0) {
+			r = init_block_ctx(token, tkl, &block_ctx);
+		} else {
+			r = get_block_ctx(token, tkl, &block_ctx);
+		}
+
+		if (r < 0) {
+			goto error;
+		}
+
+		/* 0 will be returned if it's the last block */
+		block_offset = zoap_next_block(in.in_zpkt, &block_ctx->ctx);
+	}
 
 	switch (context.operation) {
 
@@ -2315,37 +2473,63 @@ static int handle_request(struct zoap_packet *request,
 		return -EINVAL;
 	}
 
-	if (r == 0) {
-		/* TODO: Handle blockwise 1 */
+	if (r) {
+		goto error;
+	}
 
-		if (out.outlen > 0) {
-			SYS_LOG_DBG("replying with %u bytes", out.outlen);
-			zoap_packet_set_used(out.out_zpkt, out.outlen);
+	/* Handle blockwise 1 */
+	if (block_ctx) {
+		if (block_offset > 0) {
+			/* More to come, ack with correspond block # */
+			r = zoap_add_block1_option(
+					out.out_zpkt, &block_ctx->ctx);
+			if (r) {
+				/* report as internal server error */
+				SYS_LOG_ERR("Fail adding block1 option: %d", r);
+				r = -EINVAL;
+				goto error;
+			} else {
+				zoap_header_set_code(out.out_zpkt,
+						ZOAP_RESPONSE_CODE_CONTINUE);
+			}
 		} else {
-			SYS_LOG_DBG("no data in reply");
-		}
-	} else {
-		if (r == -ENOENT) {
-			zoap_header_set_code(out.out_zpkt,
-					     ZOAP_RESPONSE_CODE_NOT_FOUND);
-			r = 0;
-		} else if (r == -EPERM) {
-			zoap_header_set_code(out.out_zpkt,
-					     ZOAP_RESPONSE_CODE_NOT_ALLOWED);
-			r = 0;
-		} else if (r == -EEXIST) {
-			zoap_header_set_code(out.out_zpkt,
-					     ZOAP_RESPONSE_CODE_BAD_REQUEST);
-			r = 0;
-		} else {
-			/* Failed to handle the request */
-			zoap_header_set_code(out.out_zpkt,
-					     ZOAP_RESPONSE_CODE_INTERNAL_ERROR);
-			r = 0;
+			/* Free context when finished */
+			free_block_ctx(block_ctx);
 		}
 	}
 
-	return r;
+	if (out.outlen > 0) {
+		SYS_LOG_DBG("replying with %u bytes", out.outlen);
+		zoap_packet_set_used(out.out_zpkt, out.outlen);
+	} else {
+		SYS_LOG_DBG("no data in reply");
+	}
+
+	return 0;
+
+error:
+	if (r == -ENOENT) {
+		zoap_header_set_code(out.out_zpkt,
+				     ZOAP_RESPONSE_CODE_NOT_FOUND);
+	} else if (r == -EPERM) {
+		zoap_header_set_code(out.out_zpkt,
+				     ZOAP_RESPONSE_CODE_NOT_ALLOWED);
+	} else if (r == -EEXIST) {
+		zoap_header_set_code(out.out_zpkt,
+				     ZOAP_RESPONSE_CODE_BAD_REQUEST);
+	} else if (r == -EFBIG) {
+		zoap_header_set_code(out.out_zpkt,
+				     ZOAP_RESPONSE_CODE_REQUEST_TOO_LARGE);
+	} else {
+		/* Failed to handle the request */
+		zoap_header_set_code(out.out_zpkt,
+				     ZOAP_RESPONSE_CODE_INTERNAL_ERROR);
+	}
+
+	/* Free block context when error happened */
+	free_block_ctx(block_ctx);
+
+	return 0;
 }
 
 void lwm2m_udp_receive(struct lwm2m_ctx *client_ctx, struct net_pkt *pkt,
@@ -2788,6 +2972,9 @@ error_start:
 
 static int lwm2m_engine_init(struct device *dev)
 {
+	memset(block1_contexts, 0,
+	       sizeof(struct block_context) * NUM_BLOCK1_CONTEXT);
+
 	/* start thread to handle OBSERVER / NOTIFY events */
 	k_thread_create(&engine_thread_data,
 			&engine_thread_stack[0],
diff --git a/subsys/net/lib/lwm2m/lwm2m_engine.h b/subsys/net/lib/lwm2m/lwm2m_engine.h
index ed943a15391..bf1116afb40 100644
--- a/subsys/net/lib/lwm2m/lwm2m_engine.h
+++ b/subsys/net/lib/lwm2m/lwm2m_engine.h
@@ -103,6 +103,8 @@ void lwm2m_udp_receive(struct lwm2m_ctx *client_ctx, struct net_pkt *pkt,
 		       bool handle_separate_response,
 		       udp_request_handler_cb_t udp_request_handler);
 
+enum zoap_block_size lwm2m_default_block_size(void);
+
 #if defined(CONFIG_LWM2M_FIRMWARE_UPDATE_OBJ_SUPPORT)
 u8_t lwm2m_firmware_get_update_state(void);
 void lwm2m_firmware_set_update_state(u8_t state);
diff --git a/subsys/net/lib/lwm2m/lwm2m_obj_firmware.c b/subsys/net/lib/lwm2m/lwm2m_obj_firmware.c
index 1d0f160bc48..52b8ff252be 100644
--- a/subsys/net/lib/lwm2m/lwm2m_obj_firmware.c
+++ b/subsys/net/lib/lwm2m/lwm2m_obj_firmware.c
@@ -181,13 +181,41 @@ static int package_write_cb(u16_t obj_inst_id,
 			    u8_t *data, u16_t data_len,
 			    bool last_block, size_t total_size)
 {
-	SYS_LOG_DBG("PACKAGE WRITE");
-	if (write_cb) {
-		write_cb(obj_inst_id, data, data_len, last_block, total_size);
-		return 1;
+	u8_t state;
+	int ret = 0;
+
+	state = lwm2m_firmware_get_update_state();
+	if (state == STATE_IDLE) {
+		/* TODO: setup timer to check download status,
+		 * make sure it fail after timeout
+		 */
+		lwm2m_firmware_set_update_state(STATE_DOWNLOADING);
+	} else if (state != STATE_DOWNLOADING) {
+		if (data_len == 0 && state == STATE_DOWNLOADED) {
+			/* reset to state idle and result default */
+			lwm2m_firmware_set_update_result(RESULT_DEFAULT);
+			return 1;
+		}
+
+		SYS_LOG_DBG("Cannot download: state = %d", state);
+		return -EPERM;
 	}
 
-	return 0;
+	if (write_cb) {
+		ret = write_cb(obj_inst_id, data, data_len,
+			       last_block, total_size);
+		if (ret < 0) {
+			SYS_LOG_ERR("Failed to store firmware: %d", ret);
+			lwm2m_firmware_set_update_result(
+					RESULT_INTEGRITY_FAILED);
+		}
+	}
+
+	if (last_block) {
+		lwm2m_firmware_set_update_state(STATE_DOWNLOADED);
+	}
+
+	return 1;
 }
 
 static int package_uri_write_cb(u16_t obj_inst_id,
diff --git a/subsys/net/lib/lwm2m/lwm2m_obj_firmware_pull.c b/subsys/net/lib/lwm2m/lwm2m_obj_firmware_pull.c
index 37b4c144122..7c9e2d9ba41 100644
--- a/subsys/net/lib/lwm2m/lwm2m_obj_firmware_pull.c
+++ b/subsys/net/lib/lwm2m/lwm2m_obj_firmware_pull.c
@@ -225,28 +225,6 @@ do_firmware_transfer_reply_cb(const struct zoap_packet *response,
 	return ret;
 }
 
-static enum zoap_block_size default_block_size(void)
-{
-	switch (CONFIG_LWM2M_FIRMWARE_UPDATE_PULL_COAP_BLOCK_SIZE) {
-	case 16:
-		return ZOAP_BLOCK_16;
-	case 32:
-		return ZOAP_BLOCK_32;
-	case 64:
-		return ZOAP_BLOCK_64;
-	case 128:
-		return ZOAP_BLOCK_128;
-	case 256:
-		return ZOAP_BLOCK_256;
-	case 512:
-		return ZOAP_BLOCK_512;
-	case 1024:
-		return ZOAP_BLOCK_1024;
-	}
-
-	return ZOAP_BLOCK_256;
-}
-
 static void firmware_transfer(struct k_work *work)
 {
 	int ret, family;
@@ -325,7 +303,8 @@ static void firmware_transfer(struct k_work *work)
 	}
 
 	/* reset block transfer context */
-	zoap_block_transfer_init(&firmware_block_ctx, default_block_size(), 0);
+	zoap_block_transfer_init(&firmware_block_ctx,
+				 lwm2m_default_block_size(), 0);
 	transfer_request(&firmware_block_ctx, NULL, 0,
 			 do_firmware_transfer_reply_cb);
 	return;