The 19-year-old centre-back has made one substitute appearance for the Saints in the Premier League and is captain of the club's under-21 side.
He led Southampton to victory in last season's Premier League Under-21 Cup.
"Our last two games haven't reached our high standards defensively and he's a new option who adds competition," said Wycombe boss Gareth Ainsworth.
"Jason's a very highly-rated defender who's had good experience in the under-21s at Southampton and they feel he's ready to go out and get a taste of what senior football is like at League Two level," Ainsworth added to the club website.
Wycombe Wanderers have signed teenage Southampton defender Jason McCarthy on an initial one-month loan.