diff --git a/esphome/components/api/__init__.py b/esphome/components/api/__init__.py
index 932702d47ab..0f5cd936f54 100644
--- a/esphome/components/api/__init__.py
+++ b/esphome/components/api/__init__.py
@@ -305,6 +305,7 @@ CONFIG_SCHEMA = cv.All(
                 rtl87xx=4,  # Moderate RAM, BSD-style sockets
                 host=4,  # Abundant resources
                 ln882x=4,  # Moderate RAM
+                nrf52=4,  # ~256KB RAM, BSD sockets
             ): cv.int_range(min=1, max=10),
             cv.SplitDefault(
                 CONF_MAX_CONNECTIONS,
@@ -315,6 +316,7 @@ CONFIG_SCHEMA = cv.All(
                 rtl87xx=5,  # Moderate RAM
                 host=8,  # Abundant resources
                 ln882x=5,  # Moderate RAM
+                nrf52=4,  # ~256KB RAM, BSD sockets, Thread (single HA controller)
             ): cv.int_range(min=1, max=20),
             # Maximum queued send buffers per connection before dropping connection
             # Each buffer uses ~8-12 bytes overhead plus actual message size
diff --git a/esphome/components/api/api_pb2_includes.h b/esphome/components/api/api_pb2_includes.h
index f45e091c6f4..70ba579fcc3 100644
--- a/esphome/components/api/api_pb2_includes.h
+++ b/esphome/components/api/api_pb2_includes.h
@@ -31,6 +31,13 @@
 #include <vector>
 #include <string>
 
+#if defined(LOG_LEVEL_NONE)
+// Zephyr defines LOG_LEVEL_NONE as a logging macro that collides with the LogLevel enum value of
+// the same name in the generated api_pb2.h. Undefine it for the rest of this translation unit so
+// the enum parses; nothing below needs Zephyr's logging macro.
+#undef LOG_LEVEL_NONE
+#endif
+
 namespace esphome::api {
 
 // This file only provides includes, no actual code
diff --git a/esphome/components/network/__init__.py b/esphome/components/network/__init__.py
index b662293ab5c..846c3afc599 100644
--- a/esphome/components/network/__init__.py
+++ b/esphome/components/network/__init__.py
@@ -221,6 +221,12 @@ async def to_code(config):
         zephyr_add_prj_conf("NET_IPV6", True)
         zephyr_add_prj_conf("NET_TCP", True)
         zephyr_add_prj_conf("NET_UDP", True)
+        # The nRF Connect SDK replaces mbedTLS with PSA/Oberon crypto and does not provide the
+        # legacy mbedtls_md5() symbol that Zephyr's RFC 6528 TCP ISN generator links against
+        # (selecting MBEDTLS_MAC_MD5_ENABLED does not bring in the legacy C API here). Disable it so
+        # TCP links; Zephyr falls back to sys_rand32_get() for the ISN (randomized, but not the
+        # RFC 6528 keyed hash).
+        zephyr_add_prj_conf("NET_TCP_ISN_RFC6528", False)
 
     if (enable_ipv6 := config.get(CONF_ENABLE_IPV6, None)) is not None:
         cg.add_define("USE_NETWORK_IPV6", enable_ipv6)
diff --git a/tests/components/api/test.nrf52-adafruit.yaml b/tests/components/api/test.nrf52-adafruit.yaml
new file mode 100644
index 00000000000..9229d68aa3a
--- /dev/null
+++ b/tests/components/api/test.nrf52-adafruit.yaml
@@ -0,0 +1,4 @@
+network:
+  enable_ipv6: true
+
+api: