Dave Robson has been Button's race engineer since he joined the Woking squad back in 2010, but he is switching to a different role and will be replaced by Tom Stallard.
A McLaren spokesman has confirmed the changes, which forms part of a restructuring process at the team.
"Tom is a very intelligent and able engineer, who has worked in a variety of engineering roles within McLaren, including as Jenson Button's performance engineer," the spokesman Autosport.
"Jenson's previous race engineer was Dave Robson, who is a very experienced and expert engineer, who has achieved many successes working alongside Jenson in recent years, and whose experience and expertise will now be exploited in a broader role within McLaren's Formula 1 operation.
"This move is an example of McLaren's determination to optimize the deployment of its considerable engineering resource by developing the careers of all its engineers, on an ongoing basis, as part of our restructuring process."