Born in Feni, Mohammad Saifuddin was selected for the Under-19 World Cup in 2016, which was hosted by Bangladesh, a year after making his First-Class debut for Chittagong Division. He was named for the World Cup squad following impressive performances at the junior level. The seam-bowling all-rounder was an integral member of the Bangladesh unit which won five out of the six matches and finished third in the multi-nation tournament. That’s where a 19-year-old grabbed headlines with his performance. Saifuddin bagged 13 wickets in six innings and was Bangladesh’s highest wicket-taker in the competition.

After the U-19 World Cup, Saifuddin had a few hiccups - fitness issues and was reported for a suspect bowling action. The all-rounder fought his way out of trouble and his performances in the Asian Cricket Council Emerging Teams Cup for Bangladesh U-23 helped him receive a maiden call-up to the Bangladesh T20I side in April 2017 against Sri Lanka.

Post his T20I debut series in Sri Lanka, Saifuddin made his ODI debut against South Africa - where he played a cameo with the bat but proved to be too expensive with the ball. The team management picked him for the T20Is in the same tour and unfortunately he had to face David Miller’s wrath. Saifuddin was hit for five successive sixes in an over by Miller, who went onto smash the joint fastest T20I century (35 deliveries).

Saifuddin failed to prove his mettle in the following couple of matches he played and that resulted in him being dropped. However, contrary to popular opinion, Saifuddin was picked for the home ODI series against Zimbabwe in October 2018 and the all-rounder silenced his critics in his comeback game. With his team under pressure, Saifuddin stitched a 127-run match-winning stand with Imrul Kayes, with the former recording his maiden ODI half-century. And, in the following match, he topped it up with a Man of the Match-winning show with the ball (3/45 in 10 overs). 

Unfortunately for Saifuddin, recurring back issues and some indifferent form have curtailed his appearances at the top level. He picked up 13 wickets in 7 matches at the 2019 World Cup, but hasn't featured in the ODI format since 2021. Even his T20I appearances have been sporadic, and he even took a two-month break from cricket in 2024 after being left out of the T20 World Cup that year. He was out of the national setup for over a year before making his comeback in the T20I series against Sri Lanka in 2025.