In total, mobile sales from the top 20 brick-and-mortar retailers made up more than 17 percent of total online sales, which is an increase of 55.4 percent from a year ago, according to report.
Wal-Mart and Best Buy came in behind Apple as the top brands where consumers were actually making purchases on their smartphones and tablets.
Why are more people shopping these brands than others on mobile? Probably because their apps and mobile websites actually work.
According to the report, a bad user experience and poorly designed apps are the biggest cause for complaints when it comes to using retailers mobile apps. About 50 percent of shoppers said they are less likely to shop with a retailer if the retailer's mobile app or site is hard to use.
—By CNBC's Cadie Thompson. Follow her on Twitter @CadieThompson.