This is the concept merchants miss most often, and almost every support question about Fulfilment by Amazon traces back to it. It is worth two minutes of your time.
Look for a toggle labelled "fulfil this product with Amazon" and you will not find one. It does not exist, on the product page, in the app, or anywhere else.
Instead, you opt a product in by stocking its inventory at the "Fulfilled by Amazon (MCF)" location in Shopify.
That is the whole mechanism. The app created that location for you during setup. It is a normal Shopify location as far as Shopify is concerned, and it is where you tell the app "Amazon holds this one".
From the moment a product has its stock at that location, orders containing it are routed to Amazon FBA automatically, and you do not fulfil them yourself. Amazon picks, packs and ships them.
Products whose stock stays at your own locations are untouched. They flow through your normal workflow exactly as before. You pick them, you pack them, you buy the label. Nothing about them changes.
So the question "which products does Amazon fulfil?" has one answer: the ones stocked at the MCF location. Move stock in, and the product is in. Move it out, and it is not.
Once the guided setup is complete, opting a product in takes about thirty seconds.
That is it. There is nothing to press in Amazon Seller Sync afterwards.
If you left Keep Shopify stock in sync with Amazon FBA availability on during setup (it is on by default), you do not need to type a quantity into the MCF location either. The app pushes Amazon's fulfillable quantity into it, so Shopify shows what Amazon can actually ship, and Shopify will not let you oversell.
Do not stock the same variant at both an own location and MCF without thinking it through
If a variant has stock at your warehouse and at the MCF location, Shopify's own fulfilment routing decides where the order goes, and you may find orders splitting in ways you did not intend. For most merchants the clean pattern is: a product is either an Amazon product or a self-fulfilled product, not both.
Start with one
Opt in a single product, place a real order, and watch it move all the way to Shipped with tracking. Then expand.
The Orders tab on the Fulfilment by Amazon page lists the Shopify orders that have been handed to Amazon, so you can see what is happening without logging into Seller Central.
| Status | What it means |
|---|---|
| Sent to Amazon | The order has been passed to Amazon and accepted. Amazon has it. |
| Processing | Amazon is picking and packing it in the fulfilment centre. |
| Shipped | It has left Amazon and is with the carrier. Tracking is available. |
| Cancelled | The fulfilment was cancelled, either by you or by Amazon. |
| Returned to you | The customer sent the item back and it has been returned. |
| Reassigned to you | Amazon could not fulfil it, and because you enabled reassignment the order was moved to one of your own locations. It is now yours to ship. |
| Not fulfillable | Amazon could not fulfil it, and reassignment is off, so the order has been left in your normal workflow for you to deal with. |
| Error | Something went wrong handing the order to Amazon. Open the order to see the detail. |
The two that need action from you are Reassigned to you and Not fulfillable. In both cases Amazon is not going to ship this one, and the customer is waiting. The practical difference is that a reassigned order has already been moved to a location you nominated, while a not fulfillable order has simply been left alone. Which of the two you get depends on the If Amazon can't fulfil an order, reassign it to my own location setting described in the setup article.
When Amazon ships, it returns the carrier and the tracking number. The app writes these back onto the Shopify order, which means your customer gets Shopify's normal shipping confirmation email with working tracking, and your order shows as fulfilled. You do not need to copy anything across by hand.
The Orders card also shows the carrier and number directly, which is handy when a customer emails asking where their parcel is.
Returns against MCF orders are tracked and surfaced as a Returned count, so you can see at a glance how much of what Amazon shipped has come back. This saves digging through Seller Central to reconcile your own storefront's returns.
Where the data is available, the app shows an FBA reimbursements badge, giving the count and amount Amazon has reimbursed you. Amazon reimburses sellers when it loses or damages inventory. It is displayed here so it is visible next to the fulfilment activity it relates to rather than buried in a separate report.