im trying to buy robux with my microsoft balance in xbox but i dont see that option all i see is pay with card or redeem a giftcard theres no mention of using xbox or microsoft balance

Robux on Xbox must be purchased through the Xbox/Microsoft Store purchase flow, but not every offer or region allows paying with existing Microsoft account balance. The context confirms:

• Money is added to a Microsoft account by redeeming a gift card or code, and that balance can be used for “movies, games, in-app purchases, and physical goods,” and “Xbox-related subscription[s],” but not all products or in-app purchases are guaranteed to accept account balance as a payment method.
• Each participating store can impose additional purchase restrictions or exclusions on what can be bought with Microsoft account balance.

When the checkout screen only shows “pay with card” or “redeem a gift card” and does not show Microsoft/Xbox balance, it means that specific Robux purchase option is not eligible to be paid with existing account balance in that scenario.

To use Microsoft balance where it is supported:

1. Make sure the balance is actually in the same Microsoft account signed in on the Xbox.
2. Confirm the balance is in the same currency/region as the Xbox Store account, because balance “may only be added to a Microsoft account registered in the jurisdiction that recognizes such currency” and can only be used in that store.
3. If the store still does not offer Microsoft balance as a payment option for Robux, that purchase path does not support paying with balance and another payment method or a dedicated Roblox gift card must be used instead.

References:

• Add money to your Microsoft account
• Microsoft gift cards terms and conditions