The app now supports three different screen sizes, streaming over AirPlay, URLs within video descriptions, and offers swifter and smoother playback.
YouTube came as a pre-installed app on iOS devices until Apple pulled it, along with Google Maps, upon the release of its iOS 6 mobile operating system.
The replacement YouTube app arrived on iPhone and iPod Touch three months ago, and a downloadable Google Maps is currently in the works.
Google has also rolled out a significant update to its Gmail iOS app, giving the software the same look and feel as its desktop counterpart.
The universal YouTube app for iOS is available now a free download.