Mushfiqur Rahim's side are yet to win a one-day international in 2014 and their latest humbling defeat means they have now lost 11-successive games in the 50-over format.
Chasing 248 to win in St George's, the tourists were bowled out for 70 to give Dwayne Bravo's side an unassailable 2-0 lead in the three-match series.
Chris Gayle (58), Darren Bravo (53) and Lendl Simmons (40) impressed with the bat for the hosts to set a competitive target of 247-7.
However, Bangladesh never looked like troubling them as Kemar Roach (3-19) and Sunil Narine (3-13) consistently caused problems to the fragile batting line-up.
They lasted just 24.4 overs, losing their last seven wickets for a paltry 13 runs.
Having made an early breakthrough to remove Kirk Edwards for a duck, the Bangladesh bowlers were made to toil as Gayle and Darren Bravo built a sturdy base for the hosts to move on from.
Gayle was removed in the 22nd over by Mohammad Mahmudullah (1-47) after an explosive innings that included five sixes from his 67 balls, while Darren Bravo worked the ball into the gaps before being trapped lbw by Sohag Gazi (1-47).
Dinesh Ramdin (34), Simmons and Kieron Pollard (26) ensured the total rose just shy of 250 for the hosts.
Mashrafe Mortaza (3-39) topped the bowling figures for the tourists but he was unable to stem the flow of runs enough to keep the powerful Gayle and Pollard at bay.
West Indies' bowlers had no such problems, though, and had Bangladesh one down in the fifth over.
Wickets continued to fall at regular intervals with Tamim Iqbal (37) left fighting a lonely battle at the top of the order as batsmen came and went in quick succession.
At 57-3 the tourists still appeared to be in the game but their chances were wrecked by three wickets in six balls, including Tamim's as he clipped Kemar Roach (3-19) to Gayle at mid-wicket at the start of the 17th over.
The opener contributed more than half of Bangladesh's runs in the match with no other batsman getting into double figures in a shocking performance.
With Tamim gone there was little resistance from Bangladesh as they collapsed to the lowest total for a side bowled out in Grenada, their fate sealed with a farcical run-out that left Abdur Razzak (0 not out) stranded.
The two sides now move to St Kitts for the final match of the series with the pressure on Bangladesh to end their dreadful run of form.