Kashket, 20, joined the League Two club in August on a deal until January, but he has registered nine goals in four matches, including a hat-trick in the 5-0 triumph over Chesterfield in the second round of the FA Cup.
Wycombe manager Gareth Ainsworth said: “We gave Scott the opportunity to prove himself by giving him a deal until Christmas, and to say he has exceeded our expectations is an understatement.
“It was important for us not to miss out on the chance to extend his stay here as I’m sure there will be a lot of interest in him, and we have pushed really hard to get this deal done.”
Ainsworth admits the attacking midfielder from Chigwell has been a revelation after leaving Leyton Orient by mutual consent last summer.
“Scott has applied himself superbly and grabbed his opportunity with both hands,” he said. “The fans have seen what he’s all about – he’s a nightmare for defenders to deal with, he can score goals out of nothing.”
Kashket had a spell at Hercules in Spain in 2012 following a series of impressive displays at the European Maccabi Games in Vienna.