The centre-back has captained the Magpies to an immediate return to the Premier League this season, securing automatic promotion from the Championship at the first time of asking.
Lascelles missed Friday night's victory at Cardiff City through injury, though, and the club have now confirmed that he will undergo an operation that will rule him out of Sunday's match at home to Barnsley.
"Newcastle United can confirm that Jamaal Lascelles is set to undergo a groin operation on Tuesday evening that will see him ruled out of Sunday's season-closer at home to Barnsley," read a statement on the club's official website.
"The defender, who has captained United to Premier League promotion this term, missed Friday night's victory away to Cardiff City in preparation for his operation and is now due to return for pre-season training at the start of July."
Newcastle will win the Championship title if they better Brighton & Hove Albion's result on Sunday.