diff --git a/usr.sbin/jexec/jexec.8 b/usr.sbin/jexec/jexec.8
--- a/usr.sbin/jexec/jexec.8
+++ b/usr.sbin/jexec/jexec.8
@@ -23,7 +23,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 5, 2025
+.Dd January 11, 2026
 .Dt JEXEC 8
 .Os
 .Sh NAME
@@ -33,6 +33,7 @@
 .Nm
 .Op Fl l
 .Op Fl d Ar working-directory
+.Op Oo Fl e Ar name Ns = Ns Ar value Oc ...
 .Op Fl u Ar username | Fl U Ar username
 .Ar jail Op Ar command ...
 .Sh DESCRIPTION
@@ -66,6 +67,16 @@
 and absent the
 .Fl d
 option, commands are run from that (possibly jailed) user's directory.
+.It Fl e Ar name Ns = Ns Ar value
+Set environment variables.
+.Pp
+This parameter allows arbitrary environment variables that are available to the process
+to be executed inside of the jail, overwriting any previously defined environment variables,
+such as those specified by the
+.Fl l
+parameter.
+.Pp
+This option can be set multiple times.
 .It Fl u Ar username
 The user name from host environment as whom the
 .Ar command
diff --git a/usr.sbin/jexec/jexec.c b/usr.sbin/jexec/jexec.c
--- a/usr.sbin/jexec/jexec.c
+++ b/usr.sbin/jexec/jexec.c
@@ -59,21 +59,29 @@
 	int jid;
 	login_cap_t *lcap = NULL;
 	int ch, clean, dflag, uflag, Uflag;
+	int env_argc = argc;
+	char **env_argv = argv;
 	char *cleanenv;
 	const struct passwd *pwd = NULL;
 	const char *username, *shell, *term;
 	const char *workdir;
+	const char *jexec_args = "d:e:lnu:U:";
 
 	ch = clean = dflag = uflag = Uflag = 0;
 	username = NULL;
 	workdir = "/";
 
-	while ((ch = getopt(argc, argv, "d:lnu:U:")) != -1) {
+	while ((ch = getopt(argc, argv, jexec_args)) != -1) {
 		switch (ch) {
 		case 'd':
 			workdir = optarg;
 			dflag = 1;
 			break;
+		case 'e':
+			/* Used later. */
+			if (strchr(optarg, '=') == NULL)
+				errx(1, "%s: Invalid environment variable.", optarg);
+			break;
 		case 'l':
 			clean = 1;
 			break;
@@ -140,6 +148,19 @@
 		endpwent();
 	}
 
+	optreset = 1;
+	optind = 1;
+
+	/* Custom environment */
+	while ((ch = getopt(env_argc, env_argv, jexec_args)) != -1) {
+		switch (ch) {
+		case 'e':
+			if (putenv(optarg) == -1)
+				err(1, "putenv");
+			break;
+		}
+	}
+
 	/* Run the specified command, or the shell */
 	if (argc > 1) {
 		if (execvp(argv[1], argv + 1) < 0)
@@ -192,7 +213,7 @@
 {
 
 	fprintf(stderr, "%s\n",
-	    "usage: jexec [-l] [-d working-directory] [-u username | -U username] jail\n"
-	    "       [command ...]");
+	    "usage: jexec [-l] [-d working-directory] [[-e name=value] ...]\n"
+	    "       [-u username | -U username] jail [command ...]");
 	exit(1);
 }