The 21-year-old, who has already made 50 appearances for the club, has emerged into one of the Wasps' key players this season.
"I have been involved as a player with Wasps for around ten years now and I feel a real loyalty to the club," he told the club's official website.
"I am excited about what the future holds for this squad and with lots of young talent staying here, we are heading in a very positive direction."
Meanwhile, director of rugby Dai Young added: "I am a big fan of Sam's and his work rate and professionalism is excellent on and off the field.
"I am convinced he will be a long term regular first team player for this club with huge potential to develop further at international level if he continues to progress as well as he has."
Wasps currently sit seventh in the table.