If you're shopping for an M.2 NVMe SSD to expand your Xbox Series X|S internal storage, stop - that is not how this console expands. Xbox Series X|S uses a proprietary Seagate-made expansion card, documented by both Microsoft and Seagate, and no standard M.2 drive fits the internal expansion path. This is the single most consequential thing to know before spending money on Xbox storage, and it is the entire reason this page exists.
Updated · Microsoft and Seagate documentation checked 16 September 2026
"Add more storage and match internal storage performance of the internal SSD with the Storage Expansion Cards for XBOX Series X|S. (Sold separately, available in various sizes). Support for USB 3.1 external HDD (sold separately)."
Microsoft's own console product page, confirming the Storage Expansion Card as the internal-matching storage upgrade path, with USB 3.1 external drives named as a separate, distinct option.
Read the source →"Designed in collaboration with Microsoft, the Seagate Expansion Card for Xbox Series X|S is the only external storage device that enables users to achieve the same performance as the Xbox Velocity Architecture... The custom storage card seamlessly mirrors the functionality of the Xbox Series X and Xbox Series S internal SSDs."
Seagate's own announcement of the card it manufactures under license from Microsoft - the proprietary, custom-format expansion storage for Xbox Series X|S, distinct from a standard M.2 NVMe SSD.
Read the source →Seagate builds the card under license from Microsoft specifically so it matches the console's own internal SSD architecture - the Xbox Velocity Architecture - exactly. A general-purpose M.2 NVMe drive, however fast, is not built against that specification and does not connect to the internal expansion path at all: there is no user-accessible M.2 slot inside an Xbox Series X|S for this purpose.
"The Storage Expansion Card works exclusively with the Xbox Series X|S console." On external USB drives: "Yes: On Xbox Series X|S, your external HDD and SSD Game Drives can be used to play thousands of Original Xbox, Xbox 360, and Xbox One classics while serving as high-capacity Game Vaults for Xbox Series X|S titles. No: Games optimized for Xbox Series X|S require the Xbox Velocity Architecture. When you're ready to play those - just transfer them from your external HDD or SSD to your internal SSD or Storage Expansion Card."
Seagate's own FAQ (Seagate is Microsoft's licensed manufacturer for the card), stating the exact division of labor: USB external drives store and play back-catalogue titles; Series X|S-optimized titles require the internal SSD or the proprietary expansion card.
Read the source →Read plainly: a USB external HDD or SSD is a real, documented storage option for an Xbox Series X|S, but it plays a specific role - storing and playing back-catalogue titles (Original Xbox, Xbox 360, Xbox One) and holding current-generation games you are not actively playing. To actually play a title built for Xbox Series X|S's own architecture, Seagate's own documentation states you move it to the internal SSD or the expansion card first. See our external drives page for general USB storage picks - useful for exactly this back-catalogue and library-holding role.
We have not sourced Microsoft's own stated engineering rationale for using a proprietary card rather than a standard M.2 slot, so we are not speculating on it here. What is documented is the outcome: Seagate's own announcement frames the card as built to "seamlessly mirror the functionality of the Xbox Series X and Xbox Series S internal SSDs" - a tight coupling to the console's own Velocity Architecture that a general-purpose, off-the-shelf M.2 drive is not engineered to replicate. Whatever the underlying reasoning, the practical consequence for a buyer is unambiguous regardless of why the choice was made.
The PlayStation 5 takes the opposite path: Sony's own published M.2 SSD requirement defines a spec (PCIe Gen4 x4, a minimum sequential read threshold, a heat-dissipating structure, a size envelope) that any qualifying third-party drive can meet, rather than mandating a single proprietary product. That gives PS5 owners a genuinely competitive market of qualifying drives to shop across - which is exactly what our PS5 SSD hub is built around. Xbox Series X|S owners do not have an equivalent open market for internal expansion; the proprietary card is, per Seagate's own FAQ, the sole internally-compatible product. Two current consoles, two deliberately different answers to the same underlying question.
We do not currently track a live, in-stock listing for Seagate's Storage Expansion Card for Xbox Series X|S in our own catalogue - this is a genuinely different product category from the general M.2 NVMe SSD market this site otherwise tracks closely, and we have not yet seeded it. Rather than substitute an M.2 drive here - which would repeat the exact mistake this page exists to correct - we are stating the gap directly. Check Seagate's own product page or a major retailer for current availability and capacity options.
We would rather show this honest gap than pad it with a nearby product that does not actually answer the question a reader came here with - the whole discipline this page asks of a buyer (verify the exact product category before spending money) applies equally to how we build the page itself.
External drives for back-catalogue storage · The gaming SSD hub for PC builds · PS5 SSD for the other current console's expansion path, which does use a standard M.2 drive.
No. Microsoft's own console product page names the "Storage Expansion Cards for XBOX Series X|S" as the internal-matching upgrade path, and the card is a proprietary format manufactured by Seagate under license - not a standard M.2 NVMe SSD. There is no user-accessible M.2 slot on Xbox Series X|S for internal expansion.
Seagate, under license from Microsoft. Seagate's own 2020 announcement describes it as "designed in collaboration with Microsoft" and states it "seamlessly mirrors the functionality of the Xbox Series X and Xbox Series S internal SSDs" - a custom format built to match the console's own internal storage architecture exactly, which a general-purpose M.2 drive is not built to do.
Yes, but only for a specific purpose. Per Seagate's own FAQ: USB external HDDs and SSDs "can be used to play thousands of Original Xbox, Xbox 360, and Xbox One classics while serving as high-capacity Game Vaults for Xbox Series X|S titles" - meaning storage, not play, for current-generation titles. Games "optimized for Xbox Series X|S require the Xbox Velocity Architecture," which means transferring them to the internal SSD or the expansion card before playing.
No. Seagate's own FAQ states it plainly: "The Storage Expansion Card works exclusively with the Xbox Series X|S console."
Seagate has shipped multiple capacities since the card's 2020 launch, though we do not currently track a live, in-stock listing for this specific proprietary product in our own catalogue - see the honest note below rather than a guessed price.
We have not sourced any documentation, from Microsoft or Seagate, describing a third-party or generic alternative that works internally on Xbox Series X|S - the proprietary format is exclusive to Seagate's licensed card. We are not recommending an alternative we have not verified exists.