diff --git a/samples/openthread/coap_client/prj.conf b/samples/openthread/coap_client/prj.conf
index 91af70c837e2..36184f7f7231 100644
--- a/samples/openthread/coap_client/prj.conf
+++ b/samples/openthread/coap_client/prj.conf
@@ -28,7 +28,6 @@ CONFIG_PM_PARTITION_SIZE_SETTINGS_STORAGE=0x8000
 
 # Network sockets
 CONFIG_NET_SOCKETS=y
-CONFIG_POSIX_API=y
 CONFIG_NET_SOCKETS_POLL_MAX=4
 
 # Same network Master Key for client and server
diff --git a/samples/openthread/coap_client/src/coap_client_utils.c b/samples/openthread/coap_client/src/coap_client_utils.c
index 290939b41a41..79d4522edd84 100644
--- a/samples/openthread/coap_client/src/coap_client_utils.c
+++ b/samples/openthread/coap_client/src/coap_client_utils.c
@@ -125,7 +125,7 @@ static int on_provisioning_reply(const struct coap_packet *response,
 
 	memcpy(&unique_local_addr.sin6_addr, payload, payload_size);
 
-	if (!inet_ntop(AF_INET6, payload, unique_local_addr_str,
+	if (!zsock_inet_ntop(AF_INET6, payload, unique_local_addr_str,
 		       INET6_ADDRSTRLEN)) {
 		LOG_ERR("Received data is not IPv6 address: %d", errno);
 		ret = -errno;
diff --git a/samples/openthread/coap_server/prj.conf b/samples/openthread/coap_server/prj.conf
index 04c0b360d4c4..448651968caf 100644
--- a/samples/openthread/coap_server/prj.conf
+++ b/samples/openthread/coap_server/prj.conf
@@ -21,7 +21,6 @@ CONFIG_PM_PARTITION_SIZE_SETTINGS_STORAGE=0x8000
 
 # Network sockets
 CONFIG_NET_SOCKETS=y
-CONFIG_POSIX_API=y
 CONFIG_NET_SOCKETS_POLL_MAX=4
 
 # Same network Master Key for client and server
diff --git a/subsys/net/lib/coap_utils/coap_utils.c b/subsys/net/lib/coap_utils/coap_utils.c
index 5f574bdf8194..060eb2f5ea52 100644
--- a/subsys/net/lib/coap_utils/coap_utils.c
+++ b/subsys/net/lib/coap_utils/coap_utils.c
@@ -24,7 +24,7 @@ LOG_MODULE_REGISTER(coap_utils, CONFIG_COAP_UTILS_LOG_LEVEL);
 #endif
 
 const static int nfds = 1;
-static struct pollfd fds;
+static struct zsock_pollfd fds;
 static struct coap_reply replies[COAP_MAX_REPLIES];
 static int proto_family;
 static struct sockaddr *bind_addr;
@@ -37,7 +37,7 @@ static int coap_open_socket(void)
 	int sock;
 
 	while (1) {
-		sock = socket(proto_family, SOCK_DGRAM, IPPROTO_UDP);
+		sock = zsock_socket(proto_family, SOCK_DGRAM, IPPROTO_UDP);
 		if (sock < 0) {
 			LOG_ERR("Failed to create socket %d", errno);
 			k_sleep(K_MSEC(COAP_OPEN_SOCKET_SLEEP));
@@ -47,7 +47,7 @@ static int coap_open_socket(void)
 	}
 
 	if (bind_addr) {
-		if (bind(sock, bind_addr, sizeof(*bind_addr))) {
+		if (zsock_bind(sock, bind_addr, sizeof(*bind_addr))) {
 			LOG_ERR("Failed to bind socket, errno: %d", errno);
 		}
 	}
@@ -57,7 +57,7 @@ static int coap_open_socket(void)
 
 static void coap_close_socket(int socket)
 {
-	(void)close(socket);
+	(void)zsock_close(socket);
 }
 
 static void coap_receive(void)
@@ -73,25 +73,25 @@ static void coap_receive(void)
 	while (1) {
 		fds.revents = 0;
 
-		if (poll(&fds, nfds, -1) < 0) {
+		if (zsock_poll(&fds, nfds, -1) < 0) {
 			LOG_ERR("Error in poll:%d", errno);
 			errno = 0;
 			k_sleep(K_MSEC(COAP_POOL_SLEEP));
 			continue;
 		}
 
-		if (fds.revents & POLLERR) {
+		if (fds.revents & ZSOCK_POLLERR) {
 			LOG_ERR("Error in poll.. waiting a moment.");
 			k_sleep(K_MSEC(COAP_POOL_SLEEP));
 			continue;
 		}
 
-		if (fds.revents & POLLHUP) {
+		if (fds.revents & ZSOCK_POLLHUP) {
 			LOG_ERR("Error in poll: POLLHUP");
 			continue;
 		}
 
-		if (fds.revents & POLLNVAL) {
+		if (fds.revents & ZSOCK_POLLNVAL) {
 			LOG_ERR("Error in poll: POLLNVAL - fd not open");
 
 			coap_close_socket(fds.fd);
@@ -102,13 +102,13 @@ static void coap_receive(void)
 			continue;
 		}
 
-		if (!(fds.revents & POLLIN)) {
+		if (!(fds.revents & ZSOCK_POLLIN)) {
 			LOG_ERR("Unknown poll error");
 			continue;
 		}
 
 		from_addr_len = sizeof(from_addr);
-		len = recvfrom(fds.fd, buf, sizeof(buf) - 1, 0, &from_addr,
+		len = zsock_recvfrom(fds.fd, buf, sizeof(buf) - 1, 0, &from_addr,
 			       &from_addr_len);
 
 		if (len < 0) {
@@ -184,7 +184,7 @@ static int coap_init_request(enum coap_method method,
 static int coap_send_message(const struct sockaddr *addr,
 			     struct coap_packet *request)
 {
-	return sendto(fds.fd, request->data, request->offset, 0, addr,
+	return zsock_sendto(fds.fd, request->data, request->offset, 0, addr,
 		      sizeof(*addr));
 }
 
@@ -207,7 +207,7 @@ void coap_init(int ip_family, struct sockaddr *addr)
 		bind_addr = addr;
 	}
 
-	fds.events = POLLIN;
+	fds.events = ZSOCK_POLLIN;
 	fds.revents = 0;
 	fds.fd = coap_open_socket();