The new figures, from research grop comScore, meant it was the first time Yahoo! has beaten Google since April 2011, and is the first such victory for Yahoo! CEO and previous Google employee Marissa Meyer.
Yahoo! sites had 197 million unique US visitors last month compared with Google's 192 million, meaning 5 million more US web users visited Yahoo!'s pages.
The data also showed that Yahoo! sites were seen by 87% of the 225 million US internet users in July, a whopping statistic by any measure.
Yahoo has also picked up dozens of smaller companies since Mayer took over last year, pointing to a strong turnaround for the once-struggling company.
The statistics don't even include Tumblr, which Yahoo! acquired in May for over a billion dollars. Tumblr is a separate listing and comes in at number 28.
They also don't take into account how many people are searching, a market in which Google is still well on top, with 67% of the market in June.
Microsoft's Bing ranked second with 17% of search engine traffic in the US and Yahoo! came in third with 12%.