Apple data shows that three-quarters of the iPhones, iPads, and iPod touch devices are now running iOS 9.
According to the data published by Apple, only 19 percent of active devices - devices accessing the App Store - are running iOS 8, with a further 7 percent running iOS 7 or earlier.
Back in October of 2016 the adoption figure stood at 61 percent.
iOS 9 has hit this mark in four months, making its adoption faster than iOS 8 which took about six months to hit the same mark.
iOS 9 got off to a rocky start, with the launch being plagued by performance issue, crashes, and bugs. But since the release of iSO 9.2 back in December of last year, the lost performance and stability has returned to the platform.
iOS 9.3, which is currently in beta, will bring with it a raft of new features, including new tools to make iPads easier to administer in schools.