Maitland, who signed for the Warriors in October 2012, has made 38 appearances for the club and has scored 11 tries during his spell in Glasgow.
The 26-year-old winger has 15 caps and two tries for Scotland.
Glasgow Warriors head coach Gregor Townsend said: "Sean has played a big role at the club over the last three years and we wish him all the best when he leaves at the end of the season.
"There is still a lot of rugby to be played between now and then and I'm sure he'll want to leave the club on a high in the summer."
Sean Maitland added: "I've really enjoyed my time in Glasgow and it's been great being part of the club over the last three years.
"Since moving to Glasgow I've been selected to play for Scotland and the British & Irish Lions, so I'm grateful to Scottish Rugby for the opportunity to come over here.
"I'm looking forward to my new challenge in London next season, but all my focus will be on the Warriors until then, starting with a massive game against Bath this weekend."
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