The Republic of Ireland international won the club’s player of the season award last term – despite the Toon being relegated.
He is currently sidelined with a knee injury but snow nearing full fitness.
Elliot, who joined Newcastle from Charlton five years ago, said: “I’m delighted. Personally, I had a good run in the team last year but I was obviously gutted at the end with the injury.
“It’s a real confidence-booster that the club have put their faith in me.