It is possible. Need to attach image to product (ProductImage API), create product variant with image_id (ProductVariant API), and then create draft order (DraftOrder API) based on variant_id (option1 is mandatory) and not product_id. Otherwise if draft order is being created directly from product without variant, it seems Shopify is internally creating a variant which does not get image linked.
Topic summary
Issue: Add thumbnail images to custom line items in draft orders via the Shopify API.
Official status: Not supported. A Shopify staff reply confirms there’s no way to attach images to custom line items, and no update/roadmap was provided. A question about showing thumbnails on the checkout page (e.g., Gold/Plus) received no official solution.
Context and constraints: Community members note Shopify’s image model ties images to products/variants. Deleting a product used for an order removes the line item image, reinforcing that images aren’t stored on order lines themselves.
Workarounds suggested:
- Create a product and variant, upload an image (ProductImage), link it via image_id to the variant (ProductVariant), then create the draft order using variant_id (not a true custom line item).
- Store an image URL in line item properties (e.g., previewImgUrl) and customize the theme (Liquid) to render it in cart/line item UI (e.g., cart-notification-product.liquid). This affects theme/cart, not native checkout; Checkout Extensibility for checkout display remains unclear.
Current outcome: No native API support; feature requests persist. Last noted practice is creating a variant with a custom image/price prior to checkout. Discussion remains open.