For the 2010–11 season, Mamunul moved to Sheikh Jamal Dhanmondi Club and won his second league title.

In the middle of this quest, Atletico de Kolkata signed Mamunul on loan from Sheikh Jamal Dhanmondi Club to play the inaugural season of Indian Super League.

Mamunul moved to Sheikh Jamal Dhanmondi Club from Dhaka Mohammedan SC in 2010–11 season.

Ending his stint at Sheikh Jamal DC Mamunul Islam joined his hometown club, Chittagong Abahani on a national record fee of taka 65 lakh.

After ten long years at several clubs, Mamunul finally returned to Sky Blue Brigade in 2018.

[6] Mamunul made his debut in the inaugural season of the Indian Super League, representing Atlético de Kolkata on a three-month loan from Sheikh Jamal Dhanmondi Club,[7] becoming the only South Asian player outside India to secure a spot in the first season of the league.

Despite his promising talents, Mamunul did not receive an opportunity to start for Atlético de Kolkata in the ISL.