How to Programmatically Export Orders into CSV in Magento 2?

Step 1 : Set up a custom module.

Create module.xml file in app/code/Custom/Module/etc/.

            <?xml version="1.0"?>
                <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
                    <module name="Custom_Module" setup_version="1.0.0">
                    </module>
            </config>
                        

Create registration.php file in app/code/Custom/Module/.

            \Magento\Framework\Component\ComponentRegistrar::register(
                \Magento\Framework\Component\ComponentRegistrar::MODULE,
                'Custom_Module',
                __DIR__
            );
            

Step 2 : Create routes for your module

Create routes.xml file in app/code/Custom/Module/etc/frontend/.

            <?xml version="1.0"?>
                <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
                    <router id="standard">
                        <route frontName="custom" id="custom">
                            <module name="Custom_Module"/>
                        </route>
                    </router>
            </config>
                    

Step 3 : Create a controller to Export order Data in CSV format.

Create controller ExportOredrs.php in app/codeCustom/Module/Controller/Index/.

            <?php>
                namespace Custom\Module\Controller\Index;
                use Magento\Framework\App\Action\Action;
                use Magento\Framework\App\Action\Context;
                use Magento\Framework\App\Filesystem\DirectoryList;
                use Magento\Framework\App\Response\Http\FileFactory;
                use Magento\Sales\Api\OrderRepositoryInterface;
                use Magento\Framework\Api\SearchCriteriaBuilder;
                class ExportOrders extends Action
                    {
                       protected $fileFactory;
                       protected $orderRepository;
                       protected $searchCriteriaBuilder;
                       protected $_filesystem;

                       public function __construct(
                           Context $context,
                           FileFactory $fileFactory,
                           OrderRepositoryInterface $orderRepository,
                           SearchCriteriaBuilder $searchCriteriaBuilder,
                           \Magento\Framework\Filesystem $filesystem
                       ) {
                           $this->fileFactory = $fileFactory;
                           $this->orderRepository = $orderRepository;
                           $this->searchCriteriaBuilder = $searchCriteriaBuilder;
                           $this->_filesystem = $filesystem;
                           parent::__construct($context);
                       }

                       public function execute()
                       {
                           $searchCriteria = $this->searchCriteriaBuilder->create();
                           $orders = $this->orderRepository->getList($searchCriteria)->getItems();
                           $csvData = [];
                           $csvData[] = ['Order ID','Customer Email','Order Total'];
                           foreach ($orders as $order) {
                               $csvData[] = [
                                   $order->getEntityId(),
                                   $order->getCustomerEmail(),
                                   $order->getGrandTotal()
                               ];
                           }

                           $fileName = 'orders.csv';
                           $filePath = 'export/' . $fileName;

                           $directory = $this->_filesystem->getDirectoryWrite(DirectoryList::VAR_DIR);
                           $stream = $directory->openFile($filePath, 'w+');
                          
                           foreach ($csvData as $rowData) {
                               $stream->writeCsv($rowData);
                           }

                           $stream->close();

                           $content = [
                               'type' => 'filename',
                               'value' => $filePath,
                               'rm' => true
                           ];

                           $response = $this->fileFactory->create($fileName, $content, DirectoryList::VAR_DIR);
                           return $response;
                       }       
                    }
                    

In this controller, you can change the below data according to your need.

Ex:-If you want to add one more field like `Order Status` then you can Use below code.

                       $csvData = [];
                       $csvData[] = ['Order ID', 'Customer Email', 'Order Total', 'Order Status'];
                       foreach ($orders as $order) {
                           $csvData[] = [
                               $order->getEntityId(),
                               $order->getCustomerEmail(),
                               $order->getGrandTotal(),
                               $order->getStatus()
                           ];
                       }