Karim was promoted to district and sessions judge on 24 February 2000.[3]
On 20 October 2011, Karim was made an additional judge of the High Court Division.[3] His appointment was made permanent on 7 October 2013.[3][4]
In November 2017, Karim and Justice M Enayetur Rahim said no one was above prosecution in a hearing on a letter the administrative branch of the Bangladesh Supreme Court to the Anti Corruption Commission which suggested that the commission did not have the authority to investigate retired Supreme Court judge Md Joynul Abedin.[5][6]
In January 2023, Karim and Justice Md Mostafizur Rahman commuted the death sentence of Abdul Jalil to life sentence in the case over the murder of his wife in 2003 in Barguna District.[9]