diff --git a/src/Illuminate/Console/GeneratorCommand.php b/src/Illuminate/Console/GeneratorCommand.php
index 5b6af51a576b..d32ce8e3cd6f 100644
--- a/src/Illuminate/Console/GeneratorCommand.php
+++ b/src/Illuminate/Console/GeneratorCommand.php
@@ -2,14 +2,19 @@
 
 namespace Illuminate\Console;
 
+use Composer\Autoload\ClassLoader;
 use Illuminate\Console\Concerns\CreatesMatchingTest;
 use Illuminate\Contracts\Console\PromptsForMissingInput;
 use Illuminate\Filesystem\Filesystem;
 use Illuminate\Support\Collection;
 use Illuminate\Support\Str;
+use RuntimeException;
 use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Finder\Finder;
 
+use function Laravel\Prompts\text;
+
 abstract class GeneratorCommand extends Command implements PromptsForMissingInput
 {
     /**
@@ -117,6 +122,8 @@ abstract class GeneratorCommand extends Command implements PromptsForMissingInpu
         '__TRAIT__',
     ];
 
+    protected string $rootNamespace;
+
     /**
      * Create a new generator command instance.
      *
@@ -130,6 +137,13 @@ public function __construct(Filesystem $files)
             $this->addTestOptions();
         }
 
+        $this->getDefinition()->addOption(new InputOption(
+            'in',
+            null,
+            InputOption::VALUE_REQUIRED,
+            "Specify a namespace to generate the {$this->type} class in"
+        ));
+
         $this->files = $files;
     }
 
@@ -305,9 +319,70 @@ protected function alreadyExists($rawName)
      */
     protected function getPath($name)
     {
-        $name = Str::replaceFirst($this->rootNamespace(), '', $name);
+        try {
+            return $this->resolvePathForClass($name);
+        } catch (RuntimeException) {
+            return $this->laravel['path.base'].'/'.str_replace('\\', '/', $name).'.php';
+        }
+    }
+
+    /**
+     * Resolve the expected path for a class based on Composer autoload mappings.
+     *
+     * @throws \RuntimeException if multiple base paths match or none can be resolved
+     */
+    protected function resolvePathForClass(string $class): string
+    {
+        $namespaceRoots = [];
+
+        // Collect valid PSR-4 and PSR-0 namespace mappings
+        foreach (ClassLoader::getRegisteredLoaders() as $loader) {
+            foreach ([$loader->getPrefixesPsr4(), $loader->getPrefixes()] as $prefixes) {
+                foreach ($prefixes as $namespace => $paths) {
+                    foreach ($paths as $path) {
+                        $real = realpath($path);
+                        if ($real !== false) {
+                            $namespaceRoots[rtrim($namespace, '\\')][] = $real;
+                        }
+                    }
+                }
+            }
+        }
+
+        // Sort by namespace depth (deepest first)
+        uksort($namespaceRoots, fn ($a, $b) => Str::substrCount($b, '\\') <=> Str::substrCount($a, '\\'));
 
-        return $this->laravel['path'].'/'.str_replace('\\', '/', $name).'.php';
+        foreach ($namespaceRoots as $prefix => $paths) {
+            if (! Str::startsWith($class, $prefix)) {
+                continue;
+            }
+
+            // Filter duplicates and invalid entries
+            $paths = array_unique(array_filter($paths));
+
+            if (count($paths) > 1) {
+                throw new RuntimeException(sprintf(
+                    'Multiple base paths found for namespace [%s]: %s',
+                    $prefix,
+                    implode(', ', $paths)
+                ));
+            }
+
+            if (empty($paths)) {
+                continue;
+            }
+
+            $basePath = reset($paths);
+            $relative = ltrim(Str::after($class, $prefix), '\\');
+            $relativePath = str_replace(['\\', '_'], DIRECTORY_SEPARATOR, $relative).'.php';
+
+            return rtrim($basePath, DIRECTORY_SEPARATOR).DIRECTORY_SEPARATOR.$relativePath;
+        }
+
+        throw new RuntimeException(sprintf(
+            'Unable to resolve a base path for class [%s]',
+            $class
+        ));
     }
 
     /**
@@ -433,7 +508,20 @@ protected function getNameInput()
      */
     protected function rootNamespace()
     {
-        return $this->laravel->getNamespace();
+        if (! empty($this->rootNamespace)) {
+            return $this->rootNamespace;
+        }
+
+        $in = $this->option('in') ?? $this->laravel->getNamespace();
+        if (empty($in)) {
+            $in = text(
+                label: 'What namespace would you like to generate the '.$this->type.' in?',
+                placeholder: 'App',
+                validate: fn ($value) => empty($value) ? 'The in option is required when the application namespace is empty.' : null,
+            );
+        }
+
+        return $this->rootNamespace = trim($in, '\\').'\\';
     }
 
     /**
diff --git a/tests/Integration/Generators/TestCase.php b/tests/Integration/Generators/TestCase.php
index 19bce44b7ddb..b040d3133989 100644
--- a/tests/Integration/Generators/TestCase.php
+++ b/tests/Integration/Generators/TestCase.php
@@ -2,9 +2,21 @@
 
 namespace Illuminate\Tests\Integration\Generators;
 
+use Composer\Autoload\ClassLoader;
 use Orchestra\Testbench\Concerns\InteractsWithPublishedFiles;
 
 abstract class TestCase extends \Orchestra\Testbench\TestCase
 {
     use InteractsWithPublishedFiles;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        // Register the App namespace with Composer's autoloader for the testbench laravel app
+        $appPath = $this->app->path();
+        foreach (ClassLoader::getRegisteredLoaders() as $loader) {
+            $loader->addPsr4('App\\', [$appPath]);
+        }
+    }
 }