In the first two quarters of this year, the internet giant has already seen its shoe revenues grow 18 percent from a year ago, the firm found, based on data from the U.S. Census Bureau.
In 2016, Amazon's total shoe sales climbed by 35 percent, and this was notably without a Nike partnership nailed down nor the launch of "The Fix," Amazon's latest private-label shoe brand to hit the market.
This growth far outpaces total U.S. shoe revenues last year — including online and offline purchases, sales were only up about 5 percent.
Athletic-type shoes remain the best sellers on Amazon.com, but so-called juniors' shoes — for tweens and teens — have seen the most sales growth thus far this year, One Click Retail said. With back-to-school shopping season about to pick up, the firm expects kids' shoe sales to spike in the third quarter.
Source: One Click Retail
Notably, Adidas-branded shoes have been hot items on Amazon.com. So far in 2017, the biggest driver of growth for Amazon's shoe section has been women's sneakers from the German shoemaker. A size-seven shoe, the Adidas Women's Superstar, grew sales by a whopping 890 percent year-over-year.
Other emerging shoe brands on Amazon.com include Crocs, Clarks, Ecco, Merrell and Keen.
Amazon took its first big move into the shoe business in 2009, when it bought Zappos, which had already reached $1 billion in gross merchandise sales at the time, for $1.2 billion. One Click Retail's data only includes the sales made on Amazon.com, not Zappos.com.
Amazon wasn't immediately available to comment on the data.
Adidas CEO Kasper Rorsted joined CNBC's "Squawk on the Street" on Thursday, after his company reported an earnings beat, and discussed the sport retailer's relationship with Amazon.
"We've done business with Amazon in the U.S.," he said. But Adidas also wants to have "great relationships" with transnational retailers and promote its own website, he added. "We have to make sure consumers can buy [our] product where they want it and when."