Hi! Hope this helps. I had to find mine recently. If you go to your Facebook commerce manager and click settings, then catalog (screenshots below), you'll see it front and center.
If this helped anybody, please give my shop a look...every click helps
- Go to your Facebook Business Manager
- Click More Tools
- Click Commerce Manager
- Click Settings
- Click Catalog
- Your Shopify Catalog ID should be there.
If you don't have a Facebook Commerce Account you'll need to create one in order to set up the integrations for Facebook and Instagram Shopping. Once it is created then you can get your Catalog ID following the same steps. Praying this helps