With eight to defend in the final over, Mahmudullah claimed three wickets in four balls, but still failed to prevent Pakistan from completing the whitewash with a five-wicket win in the third T20I in Mirpur.
After Taskin Ahmed left out with an injury, Mahmudullah brought himself in to bowl the last over. He gave Bangladesh hope by dismissing Sarfaraz Ahmed and Haider Ali in successive balls before a six from Iftikhar Ahmed and a four from Mohammad Nawaz off the final ball shattered their dreams.
Chasing 125, Mohammad Rizwan (40) and Haider (45) played according to the situation after Babar Azam (19) fell to Aminul Islam (1-26) in the seventh over. They needed 26 off the final 24 balls with eight wickets in hand, but struggled to reach the target.
Despite going wicketless, Mahedi Hasan, Taskin and Nasum Ahmed conceded just 55 in their 11.1 overs to keep Bangladesh in the game, but in the end, it was not enough.
Earlier, Bangladesh batters struggled to get going again after opting to bat. Mohammad Naim took 50 balls to score 47 before being dismissed by Mohammad Wasim (2-15) in the 19th over. Shamim Hossain (22) and Afif Hossain (20) could not convert their starts into anything substantial either, as they finished on 124/7.
For Pakistan, Wasim and Iftikhar went for less than four an over for two wickets, while Usman Qadir and Haris Rauf were expensive. Shahnawaz Dahani returned 1-24.
The two sides will now play a two-match Test series, starting 26 November in Chattogram.
Brief scores: Bangladesh 124/7 in 20 overs (Mohammad Naim 47; Mohammad Wasim 2-15) lost to Pakistan 127/5 in 20 overs (Haider Ali 45; Mahmudullah 3-10) by 5 wickets with 0 balls to spare. Player of the Match: Haider Ali.
Pakistan won the series 3-0. Player of the Series: Mohammad Rizwan.