McLaren parts with long-time tester Paffett
The 33-year-old has been a test and reserve driver with the British team since 2006.
But he is staying with Mercedes in the German touring car championship DTM, while McLaren is parting company with its long-time engine supplier after Sunday's Abu Dhabi grand prix.
McLaren's new works Honda era kicks off in 2015, and the Japanese carmaker's first turbo V6 was given its track debut in an interim McLaren at Silverstone last week, with British test driver Oliver Turvey at the wheel.
McLaren's other prominent tester is Stoffel Vandoorne.
"Gary has been an excellent member of the McLaren team for the best part of a decade, and his technical input, on test track and in simulator alike, has been hugely important to us," acting McLaren CEO Jonathan Neale said.
"Just as important, he's a great guy. We wish him well."