Born in the Philippines, Smith made his Harlequins debut against London Irish at Twickenham in September 2017.
He scored 199 points in 28 matches in his debut season and has gone on to amass 1,505 in total for the club.
Smith made his full England test debut against USA in July 2021. He was part of the squad that finished third at the 2023 Rugby World Cup, often selected at full-back.
He was Steve Borthwick’s preferred fly-half in the autumn internationals, starting in all four matches against New Zealand, Australia, South Africa and Japan ahead of Sale’s George Ford.
Smith made his Harlequins return in Friday’s European Champions Cup defeat by Racing 92.
“Every time I play at The Stoop, I feel the love from the fans and their support for not only myself, but the team – I think they provide the best support this league has to offer,” he added.
“Personally, and collectively, we are all so grateful for them.
“I’ve come through the academy and still play with a lot of my best mates – hopefully we can achieve more of our dreams together.”
Harlequins are seventh in the Premiership table with three wins from their opening seven matches.
