Walmart Pay expanded its reach to around 1,000 stores on Tuesday as it rolled out in Texas and Arkansas.
Wal-Mart Store's mobile wallet allows customers to use their smartphone to pay for in-store purchases.
"We really saw a need for Walmart Pay, not to just join the mobile payment wars, but really to create a better shopping experience for our customers and eliminate those points of friction at the register," Molly Blakeman, a spokeswoman for Wal-Mart, told CNBC.
The service works with any smartphone that can download the Wal-Mart app. Users can upload store gift cards to the mobile wallet and save all of their receipts digitally. The app also allows customers to upload their receipts to "Saving Catcher" which will automatically reimburse shoppers the price difference if any of the items they have purchased were sold at a cheaper price at another retailer.
The mobile payment service, which first launched in Kansas, Missouri and Oklahoma, is slated to be released nationwide by the end of June. Blakeman said Wal-Mart is currently on track to meet that mid-year deadline.
Wal-Mart is one of several companies that have launched mobile wallet services including Google, Apple, and Samsung.