Bangladesh, fresh from their T20I clean sweep over world champions England, recorded their highest-ever ODI total as they ran up 338 for eight after being sent into bat.
Middle-order duo Shakib Al Hasan (93) and Towhid Hridoy (92) led the charge and Mushfiqur Rahim added a quickfire 44 as Bangladesh eclipsed the 333 for eight they made against Australia at the 2019 World Cup.
Graham Hume finished with figures of four for 60 but Ireland's bowlers were unable to build on the early dismissal of Bangladesh captain Tamim Iqbal for three.
Ireland made a promising start to their daunting run chase as they put on 60 for the first wicket, but once openers Stephen Doheny (34) and Paul Stirling (22) departed in quick succession, Bangladesh clinically turned the screw.
The tourists soon found themselves 76 for five and although veteran George Dockrell made 45, it only delayed the inevitable.
Ireland were eventually bowled out for 155 in the 31st over as Bangladesh stormed to victory in the opening game of the three-match series.