Former England scrum-half Danny Care has signed a new contract that will keep him at Harlequins next season.
Kea made a club record 374 first-team appearances for Quins, scoring over 100 tries.
“This is my home. I love everything about it – the rugby we play, the amazing fans and the memories we have made,” he told the club's website.
“It was an easy decision to sign the contract. We have great players who love playing together and we are building something very special.”
“We love having Danny.”
It began a storied relationship with the club, which included Premiership wins in 2012 and 2021, as well as the European Challenge Cup in 2011.
He made his international debut in 2008 and was part of the 2016 Grand Slam winning team, becoming only the sixth man to play more than 100 games for England, retiring in March with 101 caps.
Director of Rugby Billy Millard, who supported Keir to play another season, said: “Danny has been an incredible servant to our club and has shown great dedication to his exceptional professionalism, hard work and success. He is a true Harlequin who led from the front with determination.” .
“We are so happy to have Danny on our team. He is a great character and his contagious energy, combined with his experience, has made him very popular and a part of our Quinn DNA. It means being an important member.”
Keir will be hoping to help Quins reach the Premiership semi-finals again after losing to Toulouse in the European Champions Cup semi-final on Sunday.
With two games remaining, they sit fifth, level on points with fourth-placed Bristol, and travel to Exeter on Saturday to face Bristol in their final match.