diff --git a/tests/posix/env/CMakeLists.txt b/tests/posix/env/CMakeLists.txt
new file mode 100644
index 00000000000..6cd1e565dcc
--- /dev/null
+++ b/tests/posix/env/CMakeLists.txt
@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(posix_common)
+
+FILE(GLOB app_sources src/*.c)
+
+target_sources(app PRIVATE ${app_sources})
+# For setenv() and unsetenv()
+target_compile_options(app PRIVATE -U_POSIX_C_SOURCE -D_POSIX_C_SOURCE=200809L)
+# For getenv_r() visibility and testing
+target_compile_definitions(app PRIVATE _BSD_SOURCE)
diff --git a/tests/posix/env/prj.conf b/tests/posix/env/prj.conf
new file mode 100644
index 00000000000..7389f7de33e
--- /dev/null
+++ b/tests/posix/env/prj.conf
@@ -0,0 +1,3 @@
+CONFIG_ZTEST=y
+CONFIG_POSIX_ENV=y
+CONFIG_COMMON_LIBC_MALLOC=y
diff --git a/tests/posix/env/src/env.c b/tests/posix/env/src/env.c
new file mode 100644
index 00000000000..1d121a24438
--- /dev/null
+++ b/tests/posix/env/src/env.c
@@ -0,0 +1,180 @@
+/*
+ * Copyright (c) 2023, Meta
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <zephyr/ztest.h>
+
+#define M_HOME "/home/zephyr"
+#define M_UID  "1000"
+#define M_PWD  "/tmp"
+
+#define _m_alt_home "/this/path/is/much/longer/than" M_HOME
+
+#define DEFINE_ENVIRON(_handle, _key, _val) char _handle[] = _key "=" _val
+#define RESET_ENVIRON(_handle, _key, _val)                                                         \
+	snprintf(_handle, ARRAY_SIZE(_handle), "%s=%s", _key, _val)
+
+#if defined(CONFIG_NEWLIB_LIBC) || defined(CONFIG_PICOLIBC)
+/* newlib headers seem to be missing this */
+int getenv_r(const char *name, char *val, size_t len);
+#endif
+
+extern char **environ;
+static char **old_environ;
+
+static DEFINE_ENVIRON(home, "HOME", M_HOME);
+static DEFINE_ENVIRON(uid, "UID", M_UID);
+static DEFINE_ENVIRON(pwd, "PWD", M_PWD);
+
+static char *environ_for_test[] = {home, uid, pwd, NULL};
+
+ZTEST(env, test_getenv)
+{
+	zassert_equal(getenv(NULL), NULL);
+	zassert_equal(getenv(""), NULL);
+	zassert_equal(getenv("invalid=key"), NULL);
+	zassert_equal(getenv("HOME=" M_HOME), NULL);
+	zassert_equal(getenv("PWDR"), NULL);
+
+	zassert_mem_equal(getenv("HOME"), M_HOME, strlen(M_HOME) + 1);
+	zassert_mem_equal(getenv("UID"), M_UID, strlen(M_UID) + 1);
+	zassert_mem_equal(getenv("PWD"), M_PWD, strlen(M_PWD) + 1);
+}
+
+ZTEST(env, test_getenv_r)
+{
+	static char buf[16];
+	static const int exp_errno[] = {
+		EINVAL, EINVAL, EINVAL, EINVAL, ENOENT, ENOENT, ENOENT, EINVAL, EINVAL, EINVAL,
+	};
+	static const struct args_s {
+		const char *name;
+		char *buf;
+		size_t size;
+	} args[] = {
+		/* invalid input */
+		{NULL, NULL, 0},
+		{NULL, NULL, 42},
+		{NULL, buf, 0},
+		{NULL, buf, sizeof(buf)},
+		{"hello", NULL, 0},
+		{"hello", NULL, 42},
+		{"hello", buf, 0},
+
+		/* invalid names */
+		{"", buf, sizeof(buf)},
+		{"invalid=key", buf, sizeof(buf)},
+		{"HOME=", buf, sizeof(buf)},
+	};
+
+	BUILD_ASSERT(ARRAY_SIZE(exp_errno) == ARRAY_SIZE(args));
+
+	ARRAY_FOR_EACH(args, i)
+	{
+		errno = 0;
+		zassert_equal(getenv_r(args[i].name, args[i].buf, args[i].size), -1,
+			      "getenv_r(\"%s\", %p, %zu): expected to fail", args[i].name,
+			      args[i].buf, args[i].size);
+		zassert_equal(errno, exp_errno[i],
+			      "getenv_r(\"%s\", %p, %zu): act_errno: %d exp_errno: %d",
+			      args[i].name, args[i].buf, args[i].size, errno, exp_errno[i]);
+	}
+
+	zassert_mem_equal(getenv("HOME"), M_HOME, strlen(M_HOME) + 1);
+	zassert_mem_equal(getenv("UID"), M_UID, strlen(M_UID) + 1);
+	zassert_mem_equal(getenv("PWD"), M_PWD, strlen(M_PWD) + 1);
+}
+
+ZTEST(env, test_setenv)
+{
+	zassert_equal(setenv(NULL, NULL, 0), -1);
+	zassert_equal(errno, EINVAL);
+
+	/*
+	 * bug in picolibc / newlib
+	 * https://github.com/picolibc/picolibc/issues/648
+	 */
+	zassert_equal(setenv("", "42", 0), -1);
+	zassert_equal(errno, EINVAL);
+
+	zassert_equal(setenv("invalid=key", "42", 0), -1);
+	zassert_equal(errno, EINVAL);
+
+	/* do not overwrite if environ[key] exists */
+	zassert_ok(setenv("HOME", "/root", 0));
+	zassert_mem_equal(getenv("HOME"), M_HOME, strlen(M_HOME) + 1);
+
+	/* should overwrite (without malloc) */
+	zassert_ok(setenv("HOME", "/root", 1));
+	zassert_mem_equal(getenv("HOME"), "/root", strlen("/root") + 1);
+}
+
+ZTEST(env, test_unsetenv)
+{
+	/* not hardened / application should fault */
+	zassert_equal(unsetenv(NULL), -1);
+	zassert_equal(errno, EINVAL);
+
+	errno = 0;
+	/* bug in picolibc / newlib */
+	zassert_equal(unsetenv(""), -1);
+	zassert_equal(errno, EINVAL);
+
+	zassert_equal(unsetenv("invalid=key"), -1);
+	zassert_equal(errno, EINVAL);
+
+	/* restore original environ */
+	environ = old_environ;
+	/* should overwrite (requires realloc) */
+	zassert_ok(setenv("HOME", _m_alt_home, 1));
+	zassert_mem_equal(getenv("HOME"), _m_alt_home, strlen(_m_alt_home) + 1);
+	zassert_ok(unsetenv("HOME"));
+	zassert_is_null(getenv("HOME"));
+}
+
+ZTEST(env, test_watertight)
+{
+	extern size_t posix_env_get_allocated_space(void);
+
+	char buf[4];
+
+	/* restore original environ, which should support realloc, free, etc */
+	environ = old_environ;
+
+	for (int i = 0; i < 256; ++i) {
+		snprintf(buf, sizeof(buf), "%u", i);
+		zassert_ok(setenv("COUNTER", buf, 1));
+		zassert_mem_equal(getenv("COUNTER"), buf, strlen(buf));
+		zassert_ok(getenv_r("COUNTER", buf, sizeof(buf)));
+		zassert_equal(atoi(buf), i);
+		zassert_ok(unsetenv("COUNTER"));
+	}
+
+	zassert_equal(posix_env_get_allocated_space(), 0);
+}
+
+static void before(void *arg)
+{
+	old_environ = environ;
+
+	RESET_ENVIRON(home, "HOME", M_HOME);
+	RESET_ENVIRON(uid, "UID", M_UID);
+	RESET_ENVIRON(pwd, "PWD", M_PWD);
+	environ_for_test[0] = home;
+	environ_for_test[1] = uid;
+	environ_for_test[2] = pwd;
+
+	zassert_equal((environ = environ_for_test), environ_for_test);
+}
+
+static void after(void *arg)
+{
+	environ = old_environ;
+}
+
+ZTEST_SUITE(env, NULL, NULL, before, after, NULL);
diff --git a/tests/posix/env/testcase.yaml b/tests/posix/env/testcase.yaml
new file mode 100644
index 00000000000..305fdfff5f8
--- /dev/null
+++ b/tests/posix/env/testcase.yaml
@@ -0,0 +1,32 @@
+common:
+  filter: not CONFIG_NATIVE_LIBC
+  arch_exclude:
+    - posix
+  integration_platforms:
+    - qemu_riscv64
+  tags: posix
+tests:
+  portability.posix.env: {}
+  portability.posix.env.armclang_std_libc:
+    toolchain_allow: armclang
+    extra_configs:
+      - CONFIG_ARMCLANG_STD_LIBC=y
+  portability.posix.env.arcmwdtlib:
+    toolchain_allow: arcmwdt
+    extra_configs:
+      - CONFIG_ARCMWDT_LIBC=y
+  portability.posix.env.minimal:
+    extra_configs:
+      - CONFIG_MINIMAL_LIBC=y
+      - CONFIG_COMMON_LIBC_MALLOC_ARENA_SIZE=256
+  portability.posix.env.newlib:
+    platform_exclude:
+      - hifive1
+    filter: TOOLCHAIN_HAS_NEWLIB == 1
+    extra_configs:
+      - CONFIG_NEWLIB_LIBC=y
+  portability.posix.env.picolibc:
+    tags: picolibc
+    filter: CONFIG_PICOLIBC_SUPPORTED
+    extra_configs:
+      - CONFIG_PICOLIBC=y