diff --git a/docs/reference.md b/docs/reference.md
index f5e6ab996..558702897 100644
--- a/docs/reference.md
+++ b/docs/reference.md
@@ -774,8 +774,10 @@ FLAGS
                                  the local secrets storage.
       --apply-env-vars-to-build  Make the environment
                                  variables also available to the Actor build
-                                 process. When omitted, the setting currently stored
-                                 on the platform is kept.
+                                 process. Overrides the 'applyEnvVarsToBuild' field
+                                 in the '.actor/actor.json' file. When both are
+                                 omitted, the setting currently stored on the
+                                 platform is kept.
   -b, --build-tag=<value>        Build tag to be
                                  applied to the successful Actor build. By default,
                                  it is taken from the '.actor/actor.json' file.
diff --git a/docs/vars.md b/docs/vars.md
index 2ca91338e..01099ea08 100644
--- a/docs/vars.md
+++ b/docs/vars.md
@@ -74,3 +74,22 @@ You can use the CLI to manage secrets environment variables:
         ...
     }
     ```
+
+### Apply environment variables to the build
+
+By default, custom environment variables are available only at runtime. To also make them available to the Actor build process (for example, as Docker build arguments), set `applyEnvVarsToBuild` in `.actor/actor.json`:
+
+```json
+{
+  "actorSpecification": 1,
+  "name": "dataset-to-mysql",
+  "version": "0.1",
+  "buildTag": "latest",
+  "applyEnvVarsToBuild": true,
+  "environmentVariables": {
+    "MYSQL_PASSWORD": "@mySecretPassword"
+  }
+}
+```
+
+Alternatively, pass the `--apply-env-vars-to-build` flag to `apify push` for a one-off push. The flag overrides the `applyEnvVarsToBuild` field. When both are omitted, the setting currently stored on the Apify platform is kept.
diff --git a/src/commands/actors/push.ts b/src/commands/actors/push.ts
index 4b5ab64d8..6fc7fba18 100644
--- a/src/commands/actors/push.ts
+++ b/src/commands/actors/push.ts
@@ -192,8 +192,7 @@ export class ActorsPushCommand extends ApifyCommand<typeof ActorsPushCommand> {
 			default: false,
 		}),
 		'apply-env-vars-to-build': Flags.boolean({
-			description:
-				'Make the environment variables also available to the Actor build process. When omitted, the setting currently stored on the platform is kept.',
+			description: `Make the environment variables also available to the Actor build process. Overrides the 'applyEnvVarsToBuild' field in the '${LOCAL_CONFIG_PATH}' file. When both are omitted, the setting currently stored on the platform is kept.`,
 			required: false,
 		}),
 	};
@@ -411,8 +410,9 @@ Skipping push. Use --force to override.`,
 					allowMissing: this.flags.allowMissingSecrets,
 				})
 			: undefined;
-		// undefined when the flag is omitted, so the value stored on the platform is preserved
-		const applyEnvVarsToBuild = this.flags.applyEnvVarsToBuild || undefined;
+		// undefined when neither the flag nor the actor.json field is set, so the value stored on the platform is preserved
+		const applyEnvVarsToBuild =
+			this.flags.applyEnvVarsToBuild ?? (actorConfig!.applyEnvVarsToBuild as boolean | undefined);
 
 		if (actorCurrentVersion) {
 			const actorVersionModifier = { tarballUrl, sourceFiles, buildTag, sourceType, envVars, applyEnvVarsToBuild };
diff --git a/test/api/commands/push.test.ts b/test/api/commands/push.test.ts
index 31443f49e..f3649f9de 100644
--- a/test/api/commands/push.test.ts
+++ b/test/api/commands/push.test.ts
@@ -249,6 +249,61 @@ describe('[api] apify push', () => {
 		TEST_TIMEOUT,
 	);
 
+	it(
+		'should read applyEnvVarsToBuild from actor.json, with the flag taking precedence',
+		async () => {
+			const testActor = await testUserClient.actors().create(TEST_ACTOR);
+			actorsForCleanup.add(testActor.id);
+			const testActorClient = testUserClient.actor(testActor.id);
+			const actorJson = JSON.parse(readFileSync(joinPath(LOCAL_CONFIG_PATH), 'utf8'));
+
+			try {
+				actorJson.applyEnvVarsToBuild = true;
+				writeFileSync(joinPath(LOCAL_CONFIG_PATH), JSON.stringify(actorJson, null, '\t'), { flag: 'w' });
+
+				await testRunCommand(ActorsPushCommand, {
+					args_actorId: testActor.id,
+					flags_noPrompt: true,
+					flags_force: true,
+				});
+
+				const versionWithFieldTrue = await testActorClient.version(actorJson.version).get();
+
+				actorJson.applyEnvVarsToBuild = false;
+				writeFileSync(joinPath(LOCAL_CONFIG_PATH), JSON.stringify(actorJson, null, '\t'), { flag: 'w' });
+				// the actor config is cached per cwd, so mid-test rewrites need a reset
+				resetCwdCaches();
+
+				await testRunCommand(ActorsPushCommand, {
+					args_actorId: testActor.id,
+					flags_noPrompt: true,
+					flags_force: true,
+				});
+
+				const versionWithFieldFalse = await testActorClient.version(actorJson.version).get();
+
+				// the file still says false, but the flag must win
+				await testRunCommand(ActorsPushCommand, {
+					args_actorId: testActor.id,
+					flags_noPrompt: true,
+					flags_force: true,
+					flags_applyEnvVarsToBuild: true,
+				});
+
+				const versionWithFlagOverride = await testActorClient.version(actorJson.version).get();
+
+				expect(versionWithFieldTrue!.applyEnvVarsToBuild).to.be.eql(true);
+				expect(versionWithFieldFalse!.applyEnvVarsToBuild).to.be.eql(false);
+				expect(versionWithFlagOverride!.applyEnvVarsToBuild).to.be.eql(true);
+			} finally {
+				delete actorJson.applyEnvVarsToBuild;
+				writeFileSync(joinPath(LOCAL_CONFIG_PATH), JSON.stringify(actorJson, null, '\t'), { flag: 'w' });
+				await testActorClient.delete();
+			}
+		},
+		TEST_TIMEOUT,
+	);
+
 	it(
 		'should upload zip for source files larger that 3MB',
 		async () => {