Zimbabwe, far the more experienced of these two 'minnows', slumped to five for two inside two overs as they chased a modest target of 137.
But left-hander Williams, who'd impressed while making 44 in a 106-run defeat against world champions Australia on Tuesday, ensured the Africans won with 21 overs to spare as they finished on 137 for four.
Stuart Matsinkyeri was 21 not out.
Williams faced 85 balls, with two sixes and three fours.
Together with Chamu Chibhabha (30) he put on 73 for the third wicket to put Zimbabwe in sight of victory.
And when giant spinner Dwayne Leverock, who made headlines all round the world after taking two for 32 against England on Monday, came on Williams lofted him for six over mid-wicket.
However, Leverock did dismiss both Chibhabha and Elton Chigumbura.
Earlier, Janeiro Tucker's 56 was the mainstay of Bermuda's 136 after they'd collapsed to 31 for four inside 15 overs following skipper Irving Romaine's decision to bat.
Pace bowler Anthony Ireland did the damage with an opening spell of three wickets for 10 runs in six overs, including catching Glamorgan's David Hemp for nought off his own bowling. He finished with three for 22 in eight overs.
Bermuda were bowled out for 45 during a mammoth 241 run defeat by England but a fifth wicket stand of 57 between Tucker and Oliver Pitcher, who hung around for 16, prevented similar embarrassment this time.
Tucker, dropped on 48, completed his fifty before his 88-ball innings, with one six and seven fours, ended when he was caught by Terry Duffin on the boundary off Christopher Mpofu.
Bermuda gave themselves hope when Vusi Sibanda was caught and bowled by Kevin Hurdle for two before Duffin, Zimbabwe's other opener, was held in the slips by Clay Smith off Saleem Mukuddem for one.
But, ultimately, Bermuda's bowlers did not have enough runs to play with.
Zimbabwe's next match is in Jamaica where they play Ireland on March 15 in a Group D also featuring hosts West Indies and Pakistan.
Bermuda, in Group B, play Sri Lanka in Trinidad on March 15 before facing India and Bangladesh.
Bermuda 136 all out in 50 overs (J Tucker 56, Pitcher 16; Anthony Ireland 3 for 22, Mpofu 2 for 22, Dabengwa 2 for 5) lost to Zimbabwe 137 for 4 in 29 overs (Sean Williams 72, Chibhabha 30, Matsikenyeri 21 n o; Dave Leverock 2 for 54) by 6 wickets.