The 30-year-old has been a Llanelli stalwart for nearly a decade and has amassed 170 appearances for the region, scoring 19 tries.
Shingler was recalled to the Wales squad for the summer tour clashes with Tonga and Samoa earlier this year and featured in the Under Armour Series clashes with Australia, New Zealand and South Africa.
Scarlets head coach Wayne Pivac said: “Aaron is an all rounder, not only in his work ethic at training and the values he brings, but he’s also a great player and a pleasure to coach.
“He’s worked very hard at his game and has become a real leader in the group over the last 12 to 18 months, particularly when the internationals were away last season.
“He was a big part of the championship win last season and his hard work and diligence has paid dividends with him winning reselection to the Wales squad.”
Shingler impressed for Wales in the autumn, stepping up in the absence of the likes of Sam Warburton, Justin Tipuric and Ross Moriarty.
“I’m very happy to have signed a long-term deal with the Scarlets. I’m in my 10th season at the region and really enjoy playing my rugby here,” Shingler said.
“Winning the league with this group of people was a special moment last season, but we want to continue to build and develop which will lead to us hopefully winning more silverware.”
