diff --git a/doc/connectivity/bluetooth/api/connection_mgmt.rst b/doc/connectivity/bluetooth/api/connection_mgmt.rst
index 3a3d8d02a82..1b7ea2788c3 100644
--- a/doc/connectivity/bluetooth/api/connection_mgmt.rst
+++ b/doc/connectivity/bluetooth/api/connection_mgmt.rst
@@ -15,6 +15,14 @@ longer period of time, since this ensures that the object remains valid
 :c:func:`bt_conn_unref` API is to be used when releasing a reference
 to a connection.
 
+A common mistake is to forget unreleasing a reference to a connection
+object created by functions :c:func:`bt_conn_le_create` and
+:c:func:`bt_conn_le_create_synced`. To protect against this, use the
+:kconfig:option:`CONFIG_BT_CONN_CHECK_NULL_BEFORE_CREATE` Kconfig option,
+which forces these functions return an error if the connection pointer
+passed to them is not NULL. This helps to spot such issues and avoid
+sporadic bugs caused by not releasing the connection object.
+
 An application may track connections by registering a
 :c:struct:`bt_conn_cb` struct using the :c:func:`bt_conn_cb_register`
 or :c:macro:`BT_CONN_CB_DEFINE` APIs. This struct lets the application
diff --git a/doc/releases/release-notes-4.0.rst b/doc/releases/release-notes-4.0.rst
index 48f57ad7137..d27e7657cb2 100644
--- a/doc/releases/release-notes-4.0.rst
+++ b/doc/releases/release-notes-4.0.rst
@@ -123,6 +123,13 @@ Bluetooth
 
   * The host now disconnects from the peer upon ATT timeout.
 
+  * Added a warning to :c:func:`bt_conn_le_create` and :c:func:`bt_conn_le_create_synced` if
+    the connection pointer passed as an argument is not NULL.
+
+  * Added Kconfig option :kconfig:option:`CONFIG_BT_CONN_CHECK_NULL_BEFORE_CREATE` to enforce
+    :c:func:`bt_conn_le_create` and :c:func:`bt_conn_le_create_synced` return an error if the
+    connection pointer passed as an argument is not NULL.
+
 * HCI Drivers
 
 Boards & SoC Support
diff --git a/include/zephyr/bluetooth/conn.h b/include/zephyr/bluetooth/conn.h
index 4d2da8d7a58..b4cf1c5c6ba 100644
--- a/include/zephyr/bluetooth/conn.h
+++ b/include/zephyr/bluetooth/conn.h
@@ -1336,7 +1336,9 @@ struct bt_conn_le_create_param {
  *  Allows initiate new LE link to remote peer using its address.
  *
  *  The caller gets a new reference to the connection object which must be
- *  released with bt_conn_unref() once done using the object.
+ *  released with bt_conn_unref() once done using the object. If
+ *  @kconfig{CONFIG_BT_CONN_CHECK_NULL_BEFORE_CREATE} is enabled, this function
+ *  will return -EINVAL if dereferenced @p conn is not NULL.
  *
  *  This uses the General Connection Establishment procedure.
  *
@@ -1375,7 +1377,9 @@ struct bt_conn_le_create_synced_param {
  *  with Responses (PAwR) train.
  *
  *  The caller gets a new reference to the connection object which must be
- *  released with bt_conn_unref() once done using the object.
+ *  released with bt_conn_unref() once done using the object. If
+ *  @kconfig{CONFIG_BT_CONN_CHECK_NULL_BEFORE_CREATE} is enabled, this function
+ *  will return -EINVAL if dereferenced @p conn is not NULL.
  *
  *  This uses the Periodic Advertising Connection Procedure.
  *
diff --git a/subsys/bluetooth/host/Kconfig b/subsys/bluetooth/host/Kconfig
index 7f39fa5d9bb..db247d76b93 100644
--- a/subsys/bluetooth/host/Kconfig
+++ b/subsys/bluetooth/host/Kconfig
@@ -343,6 +343,17 @@ config BT_CONN_PARAM_ANY
 	  min and max connection intervals in order to verify whether the
 	  desired parameters have been established in the connection.
 
+config BT_CONN_CHECK_NULL_BEFORE_CREATE
+	bool "Check if *conn is NULL when creating a connection"
+	help
+	  Enable this option to ensure that bt_conn_le_create and
+	  bt_conn_le_create_synced return an error if *conn is not initialized
+	  to NULL. This option is recommended to use to catch programming
+	  errors where the application reuses the connection pointer of an
+	  active connection object without dereferencing it. Without
+	  dereferencing, the connection object stays alive which can lead to an
+	  unpredictable behavior.
+
 config BT_USER_PHY_UPDATE
 	bool "User control of PHY Update Procedure"
 	depends on BT_PHY_UPDATE
diff --git a/subsys/bluetooth/host/conn.c b/subsys/bluetooth/host/conn.c
index f4c4fa7f6fa..f77710b3e08 100644
--- a/subsys/bluetooth/host/conn.c
+++ b/subsys/bluetooth/host/conn.c
@@ -3720,6 +3720,23 @@ int bt_conn_le_create(const bt_addr_le_t *peer, const struct bt_conn_le_create_p
 	struct bt_conn *conn;
 	int err;
 
+	CHECKIF(ret_conn == NULL) {
+		return -EINVAL;
+	}
+
+	CHECKIF(*ret_conn != NULL) {
+		/* This rule helps application developers prevent leaks of connection references. If
+		 * a bt_conn variable is not null, it presumably holds a reference and must not be
+		 * overwritten. To avoid this warning, initialize the variables to null, and set
+		 * them to null when moving the reference.
+		 */
+		LOG_WRN("*conn should be unreferenced and initialized to NULL");
+
+		if (IS_ENABLED(CONFIG_BT_CONN_CHECK_NULL_BEFORE_CREATE)) {
+			return -EINVAL;
+		}
+	}
+
 	err = conn_le_create_common_checks(peer, conn_param);
 	if (err) {
 		return err;
@@ -3779,6 +3796,23 @@ int bt_conn_le_create_synced(const struct bt_le_ext_adv *adv,
 	struct bt_conn *conn;
 	int err;
 
+	CHECKIF(ret_conn == NULL) {
+		return -EINVAL;
+	}
+
+	CHECKIF(*ret_conn != NULL) {
+		/* This rule helps application developers prevent leaks of connection references. If
+		 * a bt_conn variable is not null, it presumably holds a reference and must not be
+		 * overwritten. To avoid this warning, initialize the variables to null, and set
+		 * them to null when moving the reference.
+		 */
+		LOG_WRN("*conn should be unreferenced and initialized to NULL");
+
+		if (IS_ENABLED(CONFIG_BT_CONN_CHECK_NULL_BEFORE_CREATE)) {
+			return -EINVAL;
+		}
+	}
+
 	err = conn_le_create_common_checks(synced_param->peer, conn_param);
 	if (err) {
 		return err;