Amazon claims Buy with Prime boosts conversion by 25% on average. That's a big number. If your Shopify store converts at 1.4% (the platform average), a 25% lift puts you at 1.75%. More sales without more ad spend.

But that number comes with asterisks. Buy with Prime adds fees on top of your Shopify costs, hands Amazon control over fulfillment and returns, and only works for US-based stores. Whether the conversion lift actually covers those costs depends on your margins, your product type, and how much control you're willing to give up.

What Is Buy with Prime on Shopify?

Buy with Prime is an Amazon service that adds the Prime badge and delivery promise directly to your Shopify product pages. When a shopper sees "FREE delivery Thursday" with the Prime checkmark, they're more likely to buy — because 200+ million Prime members already trust that badge.

Here's how it works in practice:

Your inventory lives in Amazon's fulfillment centers (FBA warehouses)
The Prime badge appears on eligible products on your Shopify store
Customers check out through your Shopify store using Amazon Pay
Amazon picks, packs, and ships the order with Prime-speed delivery
Returns are handled through Amazon's return process

The Shopify app (Amazon MCF and Buy with Prime) manages catalog sync, order routing, and return tracking from within your Shopify admin. There's no cost to install the app itself.

The Real Cost Structure (It's Not Just 3%)

The Prime service fee is 3% of each order value, with a minimum of $0.30 per order. That's the headline number. But it's not the full picture.

You'll also pay:

Fulfillment fees — per-unit fees based on product size and weight (increased by an average of $0.24/unit in 2026)
Storage fees — monthly charges for inventory sitting in Amazon warehouses
A 3.5% fuel and logistics surcharge — added May 2, 2026, applied on top of fulfillment fees
Shopify's payment processing fees — these still apply on your end

For a $40 product, you're looking at roughly $3–$6 in combined Buy with Prime fees per order, depending on size and weight. On top of your existing Shopify subscription and payment processing. That's workable on a 60% margin product. It's brutal on a 30% margin one.

Is Buy with Prime on Shopify Worth It for Your Store?

Buy with Prime works best for stores that already sell on Amazon and have inventory in FBA warehouses. You're essentially extending your existing Amazon fulfillment to your Shopify storefront without shipping products to a separate 3PL.

Good fit:

Products priced above $30 with healthy margins (50%+)
Brands already using FBA for Amazon sales
Stores where fast shipping is a key purchase driver (commoditized products, competitive categories)
Merchants focused on customer acquisition — Amazon reports 75% of Buy with Prime orders come from new shoppers

Poor fit:

Low-margin products where 3% + fulfillment fees eat your profit
Stores that don't already use FBA (sending inventory to Amazon just for this adds complexity — consider a standalone 3PL instead)
Brands where the post-purchase experience is critical to retention (Amazon controls returns)
International stores — Buy with Prime is US-only and requires USD checkout
COD merchants — the service requires Shopify Payments and Amazon Pay, neither of which support cash on delivery

The Trade-Offs Most Merchants Don't Consider

Buy with Prime's biggest trade-offs are loss of return policy control, split customer data, and partial catalog coverage. Consider each before you enable it:

You lose control over returns. Amazon handles the return experience their way — generous return windows, no questions asked. If your current return policy is more restrictive (which helps margins), Buy with Prime overrides that for orders placed through it.

Customer data gets complicated. You still see the order in Shopify, but Amazon processes the payment through Amazon Pay. You get the customer's shipping info, but the relationship feels split between two platforms.

Not all products can be enrolled. Products need to be in FBA inventory and meet Amazon's eligibility requirements. If you carry 200 SKUs but only 40 are in FBA, the Prime badge only appears on those 40.

Technical issues exist. Merchant reviews on the Shopify App Store report occasional catalog sync failures, stuck orders, and slow support response times. It's not plug-and-play for everyone.

The September 2026 Deadline You Need to Know

If you're currently using the older "Amazon MCF: US Fulfillment" app on Shopify, it will be deactivated on September 30, 2026. Amazon is consolidating everything into the newer "MCF and Buy with Prime" app.

This means you need to migrate before that date or lose your Amazon fulfillment integration entirely. The migration involves:

Installing the new MCF and Buy with Prime app from the Shopify App Store
Exporting your SKU mappings from the old app (download CSV from "Manage product catalog")
Completing onboarding in the new app and re-mapping your catalog

If you have a large catalog, start early. Merchants with hundreds of SKUs report the migration taking a few days to get right.

How to Decide: Run the Math on Your Top 10 Products

Don't enable Buy with Prime across your entire catalog. Start with your top 10 best-selling products and run this calculation for each:

Take your current conversion rate for that product page
Apply a 25% lift (Amazon's average claim) to estimate new conversions
Calculate the additional revenue from those extra sales
Subtract the Buy with Prime fees (3% service + fulfillment + storage) from that revenue
Compare the net gain to what you'd earn spending the same amount on ads instead

If the net gain is positive and meaningfully better than your ad ROAS, enable it. If it's marginal or negative, the conversion lift doesn't cover the cost for that product.

Requirements to Get Started

Before you can enable Buy with Prime on Shopify, you need:

A US-based Shopify store selling in USD
An active Shopify Payments account
Amazon Pay activated through Shopify Payments
A Shopify Basic plan or higher
Inventory stored in Amazon FBA warehouses
An Amazon Professional Seller account

If you're already selling on Amazon and using FBA, most of these are already in place. If you're starting from scratch with no Amazon presence, the setup cost (sending inventory to FBA, account setup, catalog management) may outweigh the benefits unless you're committed to multi-channel selling.

The right move for most Shopify merchants: test Buy with Prime on 5–10 high-margin, fast-selling products for 60 days. Track the actual conversion lift and calculate net profit per order with fees included. If the math works, expand. If it doesn't, you'll know within two months without committing your entire catalog. The September 2026 deadline makes now a good time to decide — either migrate to the new app and test, or remove Amazon fulfillment from your stack entirely.