Grimes struggled during his loan spell at Leeds during 2016-17.
Grimes, 23, has been integral to Swansea's campaign so far, featuring in 15 of the club's 16 Championship outings so far. He has even shown his versatility, starring in his preferred position of central midfield as well as left-back.
It is a big achievement for Grimes, who struggled during a loan spell at Leeds in 2016-17 after being lured to Elland Road by Garry Monk who he worked with at Swansea. He managed just 12 appearances throughout the whole season.
Grimes posted on Instagram after signing a new deal, with his previous contract set to see the England Under-21 international leave next summer. Former teammate Ayling commented on the post.
Grimes went on loan to Northampton Town last season, starring in League One despite the club's relegation to League Two. He clocked up 47 appearances, managing four goals and 11 assists from midfield.
Such form saw Graham Potter give Grimes a chance in Swansea's first team following their relegation to the Championship and Grimes has jumped at the opportunity - being rewarded with a new deal.