The 27-year-old, who has previously raced with the team as a junior driver, has been driving for the Mitsubishi team for the last three years, amassing impressive points-scoring positions in six of the 10 rounds to date this season.
Burns, from Oxfordshire, will replace the departing Colin McRae, who moves to Ford.
"I am very happy to return to Subaru," Burns said. "My years at Mitsubishi have put me in the position I'm now in. They gave me a full programme this year and the opportunity to prove myself. I have a lot to thank them for, but now it's time to move on and look ahead.
"Before, I was always a junior member, with Colin and Carlos Sainz leading the team, but now it's great to come back as one of the lead drivers."
David Lapworth, technical director for Subaru's world rally team, said: "We have obviously kept an eye on Richard's progress over the years and have been immensely impressed, not only with his performance in the car but also his maturity and commitment. I know he will be an enormous asset to the team."Reuse content