Hat-trick hero gets four-year contract
Saracens, the reigning European champions, said the England international's deal will keep him at Allianz Park until 2021.
George, 26, made his first-team debut for the club in 2009. He has won 17 England caps and started all three Tests for the Lions in New Zealand in June and July.
George has won back-to-back European Champions Cups and three Premiership titles with Saracens and his new deal comes just weeks after his England and Lions colleague Owen Farrell agreed a five-year contract extension with the club.
"It's the club that I have grown up playing for, the club I've grown up supporting my whole life," said George.
"To be signing here for the long term and to have played here for a long time already is a huge honour."
Saracens rugby director Mark McCall said he was delighted to have secured the player's long-term future.
"He is fast becoming a world-class player in his position and is a key figure for both club and country," he said.
"Jamie is a real example for our younger players to follow. It's well-documented how patient he had to be earlier on in his career and both Jamie and Saracens have reaped the rewards from that.
Saracens also announced new contracts for England international lock Nick Isiekwe and fly-half Max Malins, whose deals will run until 2020.