The Briton travelled to the International Space Station (ISS) in December, along with American Tim Kopra and Russian commander Yuri Malenchenko.
The trio were due to return to Earth on June 5 but will now come back on June 18, almost two weeks later than originally planned.
Mission controllers are keeping them aboard the space station to keep it fully manned with six astronauts for as long as possible during the changeover of its crews.
Another three-strong crew will take off from Earth on June 21, three days after Major Peake’s return.
He said: “Although I am looking forward to being back on Earth and seeing friends and family again, each day spent living in space is a huge privilege and there is much work to do on the station.
“This extension will keep the station at a full crew of six for several days longer, enabling us to accomplish more scientific research.
“And, of course, I get to enjoy the beautiful view of planet Earth for a little while longer.”
Tweeting his excitement on Saturday, he added: “I get to stay an extra few days in space. Looking forward to being back, but loving it here and a lot more to do!”
Major Peake blasted into space five months ago and in January became the first British person to walk in space.
Since arriving on the ISS the former Army officer has sent a number of video messages back to Earth and last week ran the London Marathon using an on-board treadmill.
On Friday he become the first person to remotely control a rover robot back on Earth from space.
He piloted the explorer through a Mars-like rocky landscape at a hangar at Airbus Defence and Space in Stevenage.
The pioneering experiment gave valuable feedback for scientists ahead of an expedition in 2018 which will see a rover land on the surface of the red planet.