Why sellers add Walmart after Amazon
Sellers add Walmart Marketplace after Amazon because it is the largest U.S. marketplace alternative and many buyers search both. The risk is that Walmart becomes a second, disconnected inventory problem: separate stock, separate forecasts and separate mistakes.
The better approach is one bulk inventory pool at a 3PL that feeds Amazon FBA, Walmart Fulfillment Services (WFS) and seller-fulfilled orders as needed, so each channel gets what it sells and nothing more.
WFS versus seller-fulfilled on Walmart
Walmart sellers can fulfill through WFS, where Walmart stores and ships inventory from its own fulfillment centers, or fulfill orders themselves or through a 3PL. Each has trade-offs.
- WFS puts inventory in Walmart's network and can help with fast-delivery badging, but you take on another set of inbound rules, fees and capacity constraints
- Seller-fulfilled through a 3PL keeps inventory in your shared pool, but you must meet Walmart's shipping speed and on-time delivery expectations yourself
Many brands start seller-fulfilled to learn demand, then move top sellers into WFS once velocity justifies it.
Prep and labeling differences
Prep and labeling for WFS is similar in spirit to FBA but not identical, so a unit prepped for Amazon is not automatically ready for Walmart. An Amazon FNSKU label identifies your inventory only inside Amazon. WFS relies on its own item identification rules, typically based on the product's GTIN barcode or a Walmart-specific label where required.
That means units must be prepped for a specific destination, not generically. The practical rule is to keep bulk inventory unlabeled or labeled only with the product barcode, and apply channel-specific labels and prep at the moment a replenishment shipment is built. Check Walmart's current WFS requirements before your first inbound, since they change.
Splitting inventory between channels
Splitting inventory works best with days-of-cover targets for each channel, managed from the same bulk stock:
- Set separate minimum and maximum cover targets for FBA and WFS per SKU
- Replenish each channel on its own cadence from the shared pool
- Keep a reserve in bulk for seller-fulfilled Walmart, DTC or wholesale orders
- Review sell-through weekly and shift allocation toward the channel that is moving faster
Because the bulk stock is unallocated until it ships, you avoid locking inventory into the wrong marketplace.
Forecasting across two marketplaces
Forecasting across Amazon and Walmart is harder than forecasting either alone, because demand shifts between them with promotions, pricing and search placement. A deal on one marketplace can pull demand away from the other for a few weeks.
For that reason, plan total demand at the SKU level first, then allocate by channel. Your factory order follows total demand. Channel allocation can change week to week from the bulk pool without touching the purchase order.
Systems and integrations
Systems should give you one view of inventory across bulk storage, FBA and WFS. At minimum, your 3PL should report on-hand bulk inventory by SKU and lot, and your marketplace data should show FBA and WFS inventory and sell-through. Many brands tie this together with an inventory planning tool or ERP.
For seller-fulfilled Walmart orders, the 3PL needs an order integration with Walmart Marketplace, directly or through a channel management or shipping platform, plus timely tracking uploads to protect your seller metrics.
When one pool beats two
One pool beats two almost every time you are buying the same SKUs for both marketplaces. You place one factory order, land one container, pay one set of receiving charges and avoid the situation where Walmart is out of stock while Amazon sits on aged inventory. The exception is a channel-exclusive SKU, which can simply live in its own allocation within the same warehouse.
Common mistakes when adding Walmart
The most common mistakes when adding Walmart are avoidable with planning:
- Pre-labeling bulk inventory with FNSKUs, which then have to be covered or replaced before the units can go anywhere other than Amazon
- Buying separate inventory for Walmart instead of allocating from a shared pool
- Sending too much into WFS before demand is proven, recreating the same storage problems sellers face in FBA
- Ignoring Walmart's seller performance standards for seller-fulfilled orders, such as on-time shipment and valid tracking
- Treating Walmart listings as a copy of Amazon listings without checking item setup, content and identifiers
Keeping bulk inventory channel-neutral is the single change that prevents most of these problems. Labels and channel-specific prep belong at the last step, when you know where the unit is going. That one discipline also keeps options open for DTC, wholesale or another marketplace later, without the rework cost of stripping labels from units that were committed to a single channel too early.
The decision to add WFS later is also easier from a shared pool. You can send a small test inbound to Walmart for a handful of proven SKUs, compare delivery speed, fees and sales lift against seller-fulfilled performance, and scale or pull back without reordering from the factory. Because nothing was committed to a channel until it shipped, the test is cheap to run and cheap to reverse. The same logic applies to any future marketplace: inventory that stays channel-neutral until the last step is inventory that can follow demand wherever it shows up.
Frequently asked questions
Can the same 3PL send inventory to both Amazon FBA and Walmart WFS?
Yes. A 3PL can hold one bulk inventory pool and build separate inbound shipments for FBA and WFS, applying each marketplace's labeling and prep at the time each shipment is created.
Is an FBA label valid for Walmart Fulfillment Services?
No. An FNSKU label identifies inventory only in Amazon's network. Walmart uses its own item identification rules, so units must be labeled for the destination channel.
Should I use WFS or fulfill Walmart orders myself?
It depends on velocity. Many sellers fulfill Walmart orders from a 3PL while demand is uncertain, then move top-selling SKUs into WFS once volume justifies another inbound program.