But just barely - in the 12-week period leading up to and after the iPhone 5's release (ending Oct. 28), iOS earned enough new users to claim 48.1 percent of the U.S. smartphone market, while Android now holds 46.7 percent, according to the report.
Apple and Android are ever at odds for the top spot, and Kantar Worldpanel's Global Consumer Insight Director Dominic Sunnebo commented in the latest report that the last time Apple stole the crown from Android was when the iPhone 4S came out in 2011.
Sunnebo added a prediction that Apple will surpass its previous high of 49.3 percent, which would mark its highest ever chunk of the market, within the next two quarters.
Huge growth for Apple
A report from digital business analytics firm comScore in early October claimed that Apple and Android's market shares were growing, though Android was still in first place as of July of 2012.
At that point, Google's mobile operating system held 52.2 percent of the U.S. market, while Apple's iOS comprised a mere 33.4 percent.
If those figures are accurate, then Tuesday's report from Kantar indicates huge growth for Apple.
That's mostly thanks to sales of the iPhone 5, 60 percent of which went to existing iPhone users looking to upgrade, while 13 percent of iPhone 5 adopters switched from Android, and 6 percent switched from BlackBerry, according to Kantar Worldpanel's research.
Android's global dominance
The previous report from Kantar was also released in October, and focused on Windows Phone's increasing traction in Europe, where it surpassed RIM's BlackBerry offerings to achieve third place overseas.
That same report indicated that Android had grown the most in the previous year, though sales of Apple's iPhone 5 had not yet been taken into account.
Midway through 2012, a different report from Kantar claimed that Android was the dominant OS worldwide, making up more than 50 percent of smartphones in several markets.
At the time, Kantar attributed that success to Android phones being cheaper and earning the loyalty of their customers.
Going back to the latest research, it seems Android remains dominant in Europe and the U.K., though Apple maintains a strong presence there as well.