Magento 2 Programatically add product to cart with additional options
The following code works.
http://i.prntscr.com/cFUE8nuRQC2Veg4i3xo9OQ.png
$productId = 4;
$additionalOptions['print_style'] = [
'label' => 'Print Style',
'value' => 'Test'
];
$params = array(
'product' => $productId,
'qty' => 1
);
$_product = $this->_productRepository->getById($productId);
$_product->addCustomOption('additional_options', $this->serializer->serialize($additionalOptions));
$this->_cart->addProduct($_product, $params);
$this->_cart->save();