You can try this
protected $_reviewFactory;
public function __construct(
...
\Magento\Review\Model\ReviewFactory $reviewFactory,
...
) {
...
$this->_reviewFactory = $reviewFactory;
...
}
public function getRatingSummary()
{
...
$this->_reviewFactory->create()->getEntitySummary($product, $this->_storeManager->getStore()->getId());
$ratingSummary = $product->getRatingSummary()->getRatingSummary();
return $ratingSummary;
}Or you can get $reviewFactory via ObjectManager (not the best solution)
$objectManager = \Magento\Framework\App\ObjectManager::getInstance();
$reviewFactory = $objectManager->create('Magento\Review\Model\Review');
$storeId = $this->_storeManager->getStore()->getId();
$reviewFactory->getEntitySummary($product, $storeId);
$ratingSummary = $product->getRatingSummary()->getRatingSummary();hope this helps others as well