At the age of 17, Mosaddek made a century in his second List A match when he scored 100 for
Abahani Limited against
Prime Doleshwar Sporting Club in 2013–14. He played one first-class match for
Dhaka Division in 2013-14 and was selected to play for
East Zone at the end of the season, when he took 3 for 65 and 4 for 33 against
South Zone. After the 2013–14 season,
Cricinfo named him as one of Bangladesh's most promising young players, noting that as a batsman he impressed "with his footwork against spin and ease against pace". Mosaddek played for
Barisal Division in the 2014-15
National Cricket League. Against
Rangpur Division at
Savar he scored 250 off 448 balls, adding 423 for the fifth wicket with
Al-Amin. In his next innings a few days later on the neighbouring cricket ground, Mosaddek scored 282 off 309 balls. Both matches were drawn. In the second innings of the last match of the season, he scored 119 for
South Zone in the
Bangladesh Cricket League, taking him past 1000 for the season and his career. Mosaddek began 2015–16 with 122 (including six
sixes) and 40 for Barisal Division, top-scoring in each innings, and scoring the first century of the worldwide 2015–16 season. In the next match, he scored 200 not out (with seven sixes) and 61, again top-scoring in each innings. Both matches were drawn. His 200 not out made him the first Bangladesh batsman to score three first-class double-centuries. Mosaddek toured
South Africa and
Zimbabwe with
Bangladesh A in October–November 2015. He was Bangladesh A's top-scorer in the two first-class matches, against
Zimbabwe A, with 194 runs at 64.66. In October 2018, Mossadek was named in the squad for the
Chittagong Vikings team, following the draft for the
2018–19 Bangladesh Premier League. He captained
Abahani Limited to victory in the
2018–19 Dhaka Premier Division Cricket League. In November 2019, he was selected to play for the
Sylhet Thunder in the
2019–20 Bangladesh Premier League. Mosaddek played for Gazi Group Chattogram in Bangabandhu T20 cup. ==International career==