Born in Charbhadrasan Upazila of Faridpur District, Morsalin started playing local football tournaments while still only being a 6th grade student of Adarsh Secondary School.
In 2014, when trials for the U-12 national football team were held in Charbhadrasan, Morsalin caught the eye of veteran coach Abul Kashem Bholer.
In 2015, with the help of his uncle Subahan Rahman, Morsalin's career resumed, when the BFF youth football coach Abdur Razzak saw his potential during a trial and included him in the U-13 national team, for the Mogh Cup held in Malaysia.
In his first year playing domestic football, Morsalin captained the club to promotion as league champions, and also finished the season as top scorer, with 19 goals from 16 matches.
[3] In 2021, Morsalin was among the 35 preliminary selected players for FC Bayern Munich's World Squad, however, he failed to make the final team.
While still being a student at BKSP, the initial plan for Morsalin was to train at the club for three years under foreign coaches, and then play in the Premier League.
However, club president Imrul Hassan sent him on loan to Mohammedan SC, during the mid season transfer window, to give him game time.
[10] On 15 August 2023, Morsalin made his continental football debut by coming on as an 84th-minute substitute during a 0–2 defeat against Sharjah FC in the 2023–24 AFC Champions League qualifying play-offs.
[11] On 20 September 2023, Morsalin and four of his teammates were discovered to have illegally brought in 64 bottles of alcohol by customs officials at Shahjalal International Airport in Dhaka.
He has stated his interest in pursuing higher studies alongside playing professional football, and also that he has had the full support of his club, Bashundhara Kings.