A 185 cm point guard, he won the Icelandic Basketball Cup in 2013 and 2015 as a member of Stjarnan.

Dagur Kár played the 2015–16 season[1] with St. Francis College where he averaged 4.6 points and 1.3 assists in 18.2 minutes per game.

[6] For the 2017–18 season, Dagur Kár averaged 16.6 points and 6.7 assists but Grindavík was knocked out in the first round of the playoffs.

On 20 April 2018 he exercised an escape clause in his contract and left Grindavík to sign back with his hometown club of Stjarnan,[7] much to the dismay of Grindavík's board as they claimed that he had stated to them that he would stay at the club for next season.

[8] In July 2018, it was reported that he had signed with Raiffeisen Flyers Wels of the Österreichische Basketball Bundesliga.

[10] He helped the Flyer Wels finish fifth in the league and reach the playoffs where it fell out in the first round.