How do I transfer my Apple Store Gift Card balance to the Apple Store App?

Was this the new USA Apple Gift Card? If so, you just make your purchase and your AppleID balance will be deducted from. Since last July in the USA, there is just Apple Gift Card and the older Apple Store gift card and separate iTunes Gift Card were discontinued. The current Apple gift card can be used in an Apple store or any of the online Apple stores.

See -> Apple Gift Card - Apple

Sorry then. You’re stuck with the older restriction that Apple Store gift cards can be used for in store purchases, but not online purchases.

Hi,

If you redeemed an App Store & iTunes gift card on your Apple ID, and you want to buy something on Apple Store App, please note it’s actually impossible.