He returned to Apple in 2009 and led Mac OS X engineering. On March 23, 2011, Federighi succeeded Bertrand Serlet as vice president of Mac Software Engineering at Apple, and on August 27, 2012 he was promoted to senior vice president, reporting to CEO Tim Cook. On October 29, 2012, upon the announcement of Scott Forstall's departure from Apple, his role was expanded to encompass iOS in addition to Mac Software Engineering. As such, he has been credited for leading the development of OS X and iOS user interfaces towards a more minimalist direction, featuring extensive use of negative space, text replacing icons, brighter colours and translucency effects.
Within the community of Apple users and developers, Federighi is known for his energetic presentations of new Apple software, frequently featuring absurdist humour such as references to his somewhat bouffant hair, use of new software features to organise implausible events such as office karaoke parties and camping trips, and his claimed love of the band Rush. He introduced iOS 7 and OS X Mavericks at Apple's developer conference WWDC 2013 and iOS 8 and OS X Yosemite at WWDC 2014, where he delivered most of the main two hour presentation.