Sylhet: Liton Das and Tamim Iqbal, 128 not out, combined for 292 in the opening stand, the team's highest ODI partnership for any wicket. Bangladesh remarkably put up 322-3 in a game which became 43-0vers-a-side after rain halted the match for 2 1/2 hours.
Zimbabwe was set 342 to win from 43 overs to avoid the clean sweep for a fourth straight time at the hands of Bangladesh. But it could manage only 218 in 37.3 overs.
Das faced 143 balls and smashed 16 fours and eight sixes for his third ODI century and second in the series. His 176 replaced as Bangladesh's highest individual score the 158 by Iqbal three days ago.
Iqbal's 13th ODI century and second in as many matches came off 109 balls. He hit seven fours and six sixes.
Das and Iqbal had their stand on 182 when rain stopped the game in the 34th over. They added 110 runs in 7.3 more overs before being separated.
Das completed his century before the interruption, and was reprieved on 107 by a no-ball, and dropped on 122 and 144 by Sikandar Raza and Wesley Madhevere respectively. He was finally caught by Raza at long on off Carl Mumba, ending the record partnership, the third best opening stand in ODI history.
Mumba later took the wicket of Mahmudullah (3) and debutant Afif Hossain (7) to finish with 3-69 off eight overs.
Bangladesh won the first match by a record 169-run margin, and the second match by four runs.
In his last match as ODI captain, Mashrafe Mortaza earned his 50th win by giving Bangladesh the breakthrough in Zimbabwe's reply, dismissing opener Tinashe Kamunhukmawe for 4.
Mohammad Saifuddin removed out-of-form Brendan Taylor for 14 and finished with a career-best 4-41. With left-arm spinner Taijul Islam claiming 2-38, the bowlers didn't allow Zimbabwe to produce a significant partnership. The best was 46.
Sikandar Raza fought hard before he was the ninth batsman out for 61 off 50. Wesley Madhevere made 42.