In a disappointing display of batting, Ireland only managed to score 101 runs in 28.1 overs in the third and final ODI of the three-match series in Sylhet on Thursday.
Hasan Mahmud, the right-arm pacer, recorded his maiden five-wicket haul, conceding 32 runs in 8.1 overs.
Ireland won the toss for the third time in the series and opted to bat first, unlike the first two matches.
Stephen Doheny was the first to fall, caught by Mushfiqur Rahim off the bowling of Hasan for just 8 runs. Paul Stirling followed soon after, also dismissed by Mahmud, this time leg before wicket for 7 runs.
Irish batting order continued to struggle as Andy Balbirnie was caught by Najmul Hossain Shanto at the slip cordon off the bowling of Taskin Ahmed for 6 runs, and Harry Tector was dismissed leg before wicket by Mahmud for a duck. Lorcan Tucker showed some resistance, scoring 28 runs before also falling leg before wicket, this time to Ebadot Hossain.
Read more: Ireland win toss, bat 1st in 3rd ODI against Bangladesh
The only bright spot for Ireland was Curtis Campher's knock of 36 runs, which included 4 boundaries. However, he was eventually caught by Taskin Ahmed off the bowling of Hasan. The remaining Irish batters failed to make any significant contributions.
Hasan was the pick of the bowlers for Bangladesh, taking 5 wickets for 32 runs in 8.1 overs. Taskin Ahmed and Ebadot Hossain also chipped in with 3 and 2 wickets respectively, while Nasum Ahmed and Mehidy Hasan Miraz went wicketless.
Bangladesh now have an easy target to chase to seal the series as they won the first match and the second match was washed away due to rain.