diff --git a/include/net/lwm2m.h b/include/net/lwm2m.h
index d4846439115..10bce646a53 100644
--- a/include/net/lwm2m.h
+++ b/include/net/lwm2m.h
@@ -24,6 +24,7 @@
 #define ZEPHYR_INCLUDE_NET_LWM2M_H_
 
 #include <kernel.h>
+#include <sys/mutex.h>
 #include <net/coap.h>
 
 /**
@@ -69,6 +70,7 @@ struct lwm2m_ctx {
 	struct coap_pending pendings[CONFIG_LWM2M_ENGINE_MAX_PENDING];
 	struct coap_reply replies[CONFIG_LWM2M_ENGINE_MAX_REPLIES];
 	struct k_delayed_work retransmit_work;
+	struct sys_mutex send_lock;
 
 #if defined(CONFIG_LWM2M_DTLS_SUPPORT)
 	/** TLS tag is set by client as a reference used when the
diff --git a/subsys/net/lib/lwm2m/lwm2m_engine.c b/subsys/net/lib/lwm2m/lwm2m_engine.c
index 0126604d5aa..4c2357d25d4 100644
--- a/subsys/net/lib/lwm2m/lwm2m_engine.c
+++ b/subsys/net/lib/lwm2m/lwm2m_engine.c
@@ -26,6 +26,7 @@ LOG_MODULE_REGISTER(LOG_MODULE_NAME);
 #include <ctype.h>
 #include <errno.h>
 #include <init.h>
+#include <sys/mutex.h>
 #include <sys/printk.h>
 #include <net/net_ip.h>
 #include <net/http_parser_url.h>
@@ -994,6 +995,8 @@ cleanup:
 
 int lwm2m_send_message(struct lwm2m_message *msg)
 {
+	int rc;
+
 	if (!msg || !msg->ctx) {
 		LOG_ERR("LwM2M message is invalid.");
 		return -EINVAL;
@@ -1005,11 +1008,16 @@ int lwm2m_send_message(struct lwm2m_message *msg)
 
 	msg->send_attempts++;
 
-	if (send(msg->ctx->sock_fd, msg->cpkt.data, msg->cpkt.offset, 0) < 0) {
+	sys_mutex_lock(&msg->ctx->send_lock, K_FOREVER);
+	rc = send(msg->ctx->sock_fd, msg->cpkt.data, msg->cpkt.offset, 0);
+	sys_mutex_unlock(&msg->ctx->send_lock);
+	if (rc < 0) {
 		if (msg->type == COAP_TYPE_CON) {
 			coap_pending_clear(msg->pending);
 		}
 
+		LOG_ERR("Failed to send packet, err %d", errno);
+
 		return -errno;
 	}
 
@@ -3769,11 +3777,22 @@ static void retransmit_request(struct k_work *work)
 
 	LOG_INF("Resending message: %p", msg);
 	msg->send_attempts++;
+
+	sys_mutex_lock(&client_ctx->send_lock, K_FOREVER);
+
+	if (msg->ctx == NULL) {
+		LOG_INF("Response for %p already handled", msg);
+		goto next_locked;
+	}
+
 	if (send(msg->ctx->sock_fd, msg->cpkt.data, msg->cpkt.offset, 0) < 0) {
 		LOG_ERR("Error sending lwm2m message: %d", -errno);
 		/* don't error here, retry until timeout */
 	}
 
+next_locked:
+	sys_mutex_unlock(&client_ctx->send_lock);
+
 next:
 	pending = coap_pending_next_to_expire(client_ctx->pendings,
 					      CONFIG_LWM2M_ENGINE_MAX_PENDING);
@@ -4055,6 +4074,7 @@ int lwm2m_engine_context_close(struct lwm2m_ctx *client_ctx)
 void lwm2m_engine_context_init(struct lwm2m_ctx *client_ctx)
 {
 	k_delayed_work_init(&client_ctx->retransmit_work, retransmit_request);
+	sys_mutex_init(&client_ctx->send_lock);
 }
 
 /* LwM2M Socket Integration */