diff --git a/apps/generator-cli/src/app/app.module.spec.ts b/apps/generator-cli/src/app/app.module.spec.ts
index 6141d26e853..3a7224deebb 100644
--- a/apps/generator-cli/src/app/app.module.spec.ts
+++ b/apps/generator-cli/src/app/app.module.spec.ts
@@ -114,6 +114,67 @@ describe('AppModule', () => {
           expect(programMock.parse).toHaveBeenNthCalledWith(1, process.argv);
         });
       });
+
+      describe('a custom generator is provided', () => {
+        beforeEach(async () => {
+          process.argv = [
+            'foo',
+            'baz',
+            '--custom-generator',
+            '/path/to/custom.jar',
+          ];
+          programMock.parse.mockImplementation(() => {
+            expect(passThroughServiceMock.init).toHaveBeenCalledTimes(1);
+          });
+          versionManagerServiceMock.getSelectedVersion.mockReturnValue('1.2.3');
+          await fixture.onApplicationBootstrap();
+        });
+
+        it('does not search for the latest version', () => {
+          expect(versionManagerServiceMock.search).toHaveBeenCalledTimes(0);
+        });
+
+        it('does not set the selected version', () => {
+          expect(
+            versionManagerServiceMock.setSelectedVersion,
+          ).toHaveBeenCalledTimes(0);
+        });
+
+        it('does not download', () => {
+          expect(
+            versionManagerServiceMock.downloadIfNeeded,
+          ).toHaveBeenCalledTimes(0);
+        });
+
+        it('parses the command', () => {
+          expect(programMock.parse).toHaveBeenNthCalledWith(1, process.argv);
+        });
+      });
+
+      describe('a custom generator is provided with = syntax', () => {
+        beforeEach(async () => {
+          process.argv = [
+            'foo',
+            'baz',
+            '--custom-generator=/path/to/custom.jar',
+          ];
+          programMock.parse.mockImplementation(() => {
+            expect(passThroughServiceMock.init).toHaveBeenCalledTimes(1);
+          });
+          versionManagerServiceMock.getSelectedVersion.mockReturnValue('1.2.3');
+          await fixture.onApplicationBootstrap();
+        });
+
+        it('does not download', () => {
+          expect(
+            versionManagerServiceMock.downloadIfNeeded,
+          ).toHaveBeenCalledTimes(0);
+        });
+
+        it('parses the command', () => {
+          expect(programMock.parse).toHaveBeenNthCalledWith(1, process.argv);
+        });
+      });
     });
   });
 });
diff --git a/apps/generator-cli/src/app/app.module.ts b/apps/generator-cli/src/app/app.module.ts
index 10c40be94f5..a2f928f51d1 100644
--- a/apps/generator-cli/src/app/app.module.ts
+++ b/apps/generator-cli/src/app/app.module.ts
@@ -63,17 +63,25 @@ export class AppModule implements OnApplicationBootstrap {
   ) {}
 
   onApplicationBootstrap = async () => {
-    let selectedVersion = this.versionManager.getSelectedVersion();
+    const hasCustomGenerator = process.argv.some(
+      (arg) =>
+        arg === '--custom-generator' || arg.startsWith('--custom-generator='),
+    );
 
-    if (!selectedVersion) {
-      const [{ version }] = await this.versionManager
-        .search(['latest'])
-        .toPromise();
-      await this.versionManager.setSelectedVersion(version);
-      selectedVersion = version;
+    if (!hasCustomGenerator) {
+      let selectedVersion = this.versionManager.getSelectedVersion();
+
+      if (!selectedVersion) {
+        const [{ version }] = await this.versionManager
+          .search(['latest'])
+          .toPromise();
+        await this.versionManager.setSelectedVersion(version);
+        selectedVersion = version;
+      }
+
+      await this.versionManager.downloadIfNeeded(selectedVersion);
     }
 
-    await this.versionManager.downloadIfNeeded(selectedVersion);
     await this.passThroughService.init();
     this.program.parse(process.argv);
   };
diff --git a/apps/generator-cli/src/app/services/generator.service.spec.ts b/apps/generator-cli/src/app/services/generator.service.spec.ts
index fd574b6cc9c..994d126eda0 100644
--- a/apps/generator-cli/src/app/services/generator.service.spec.ts
+++ b/apps/generator-cli/src/app/services/generator.service.spec.ts
@@ -116,7 +116,9 @@ describe('GeneratorService', () => {
 
       beforeEach(() => {
         executedCommands = [];
-        fs.existsSync.mockImplementation((p) => !!config[p]);
+        fs.existsSync.mockImplementation(
+          (p) => p === '/path/to/4.2.1.jar' || !!config[p],
+        );
         fs.readJSONSync.mockImplementation((p) => config[p]);
         glob.sync.mockImplementation((g) => specFiles[g]);
         concurrently.mockImplementation((ec, cfg) => {
@@ -275,6 +277,38 @@ describe('GeneratorService', () => {
           expect(returnValue).toEqual(expectedCommands.length > 0);
         });
       });
+
+      describe('custom jar only (standard jar missing)', () => {
+        let returnValue: boolean;
+
+        beforeEach(async () => {
+          fs.existsSync.mockImplementation((p) => {
+            if (p === '/path/to/4.2.1.jar') return false;
+            return !!config[p];
+          });
+          configGet.mockImplementation(
+            (path, defaultValue) => config['bar.json'] || defaultValue,
+          );
+          returnValue = await fixture.generate('../some/custom.jar');
+        });
+
+        it('uses only the custom jar', () => {
+          expect(executedCommands).toEqual([
+            {
+              name: '[bar] api/cat.yaml',
+              command: `java -jar "../some/custom.jar" generate --input-spec="${cwd}/api/cat.yaml" --output="bar/cat" --some-bool`,
+            },
+            {
+              name: '[bar] api/bird.json',
+              command: `java -jar "../some/custom.jar" generate --input-spec="${cwd}/api/bird.json" --output="bar/bird" --some-bool`,
+            },
+          ]);
+        });
+
+        it('resolved to true', () => {
+          expect(returnValue).toEqual(true);
+        });
+      });
     });
   });
 });
diff --git a/apps/generator-cli/src/app/services/generator.service.ts b/apps/generator-cli/src/app/services/generator.service.ts
index 83abc0f8b0c..07699304bdd 100644
--- a/apps/generator-cli/src/app/services/generator.service.ts
+++ b/apps/generator-cli/src/app/services/generator.service.ts
@@ -242,11 +242,16 @@ export class GeneratorService {
     }
 
     const cliPath = this.versionManager.filePath();
-    const subCmd = customGenerator
-      ? `-cp "${[cliPath, customGenerator].join(
-          this.isWin() ? ';' : ':'
-        )}" org.openapitools.codegen.OpenAPIGenerator`
-      : `-jar "${cliPath}"`;
+    let subCmd: string;
+    if (customGenerator) {
+      subCmd = fs.existsSync(cliPath)
+        ? `-cp "${[cliPath, customGenerator].join(
+            this.isWin() ? ';' : ':'
+          )}" org.openapitools.codegen.OpenAPIGenerator`
+        : `-jar "${customGenerator}"`;
+    } else {
+      subCmd = `-jar "${cliPath}"`;
+    }
     return ['java', process.env['JAVA_OPTS'], subCmd, 'generate', appendix]
       .filter((str): str is string => str != null && typeof str === 'string')
       .join(' ');
diff --git a/apps/generator-cli/src/app/services/pass-through.service.spec.ts b/apps/generator-cli/src/app/services/pass-through.service.spec.ts
index 36780b86340..36e1c034fed 100644
--- a/apps/generator-cli/src/app/services/pass-through.service.spec.ts
+++ b/apps/generator-cli/src/app/services/pass-through.service.spec.ts
@@ -8,8 +8,11 @@ import { VersionManagerService } from './version-manager.service';
 import { ConfigService } from './config.service';
 
 jest.mock('child_process');
+jest.mock('fs');
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const childProcess = jest.mocked(require('child_process'));
+// eslint-disable-next-line @typescript-eslint/no-var-requires
+const fs = jest.mocked(require('fs'));
 
 describe('PassThroughService', () => {
   let fixture: PassThroughService;
@@ -56,6 +59,7 @@ describe('PassThroughService', () => {
     fixture = moduleRef.get(PassThroughService);
 
     childProcess.spawn.mockReset().mockReturnValue({ on: jest.fn() });
+    fs.existsSync.mockReset().mockReturnValue(true);
     configServiceMock.get.mockClear();
     configServiceMock.get.mockReset();
     configServiceMock.useDocker = false;
@@ -232,6 +236,23 @@ describe('PassThroughService', () => {
             );
           });
 
+          it('can delegate with custom jar only when standard jar is missing', async () => {
+            fs.existsSync.mockReturnValue(false);
+            await program.parseAsync(
+              [name, ...argv, '--custom-generator=../some/custom.jar'],
+              { from: 'user' }
+            );
+
+            expect(childProcess.spawn).toHaveBeenNthCalledWith(
+              1,
+              `java -jar "../some/custom.jar" ${name} ${argv.join(' ')}`,
+              {
+                stdio: 'inherit',
+                shell: true,
+              }
+            );
+          });
+
           if (name === 'generate') {
             it('can delegate with custom jar to generate command', async () => {
               await program.parseAsync(
diff --git a/apps/generator-cli/src/app/services/pass-through.service.ts b/apps/generator-cli/src/app/services/pass-through.service.ts
index 75a462c5f3f..dafee5437a4 100644
--- a/apps/generator-cli/src/app/services/pass-through.service.ts
+++ b/apps/generator-cli/src/app/services/pass-through.service.ts
@@ -2,6 +2,7 @@ import { Inject, Injectable } from '@nestjs/common';
 import chalk from 'chalk';
 import { exec, spawn } from 'child_process';
 import { Command } from 'commander';
+import * as fs from 'fs';
 import { COMMANDER_PROGRAM, LOGGER } from '../constants';
 import { GeneratorService } from './generator.service';
 import { VersionManagerService } from './version-manager.service';
@@ -139,14 +140,21 @@ export class PassThroughService {
       ].join(' ');
     }
 
-    const customGenerator = this.program.opts()?.customGenerator;
+    const customGenerator =
+      this.program.opts()?.customGenerator ||
+      this.getCustomGeneratorFromArgs();
     const cliPath = this.versionManager.filePath();
 
-    const subCmd = customGenerator
-      ? `-cp "${[cliPath, customGenerator].join(
-          this.isWin() ? ';' : ':'
-        )}" org.openapitools.codegen.OpenAPIGenerator`
-      : `-jar "${cliPath}"`;
+    let subCmd: string;
+    if (customGenerator) {
+      subCmd = fs.existsSync(cliPath)
+        ? `-cp "${[cliPath, customGenerator].join(
+            this.isWin() ? ';' : ':'
+          )}" org.openapitools.codegen.OpenAPIGenerator`
+        : `-jar "${customGenerator}"`;
+    } else {
+      subCmd = `-jar "${cliPath}"`;
+    }
 
     return ['java', process.env['JAVA_OPTS'], subCmd]
       .filter((str): str is string => str != null && typeof str === 'string')
@@ -157,5 +165,18 @@ export class PassThroughService {
     console.log(chalk.cyanBright(cmd.helpInformation()));
   }
 
+  private getCustomGeneratorFromArgs(): string | undefined {
+    for (let i = 0; i < process.argv.length; i++) {
+      const arg = process.argv[i];
+      if (arg === '--custom-generator' && i + 1 < process.argv.length) {
+        return process.argv[i + 1];
+      }
+      if (arg.startsWith('--custom-generator=')) {
+        return arg.substring('--custom-generator='.length);
+      }
+    }
+    return undefined;
+  }
+
   private isWin = () => process.platform === 'win32';
 }