Edwards snared three wickets for 42 runs from his allotment of 10 overs, as Zimbabwe, chasing 334 for victory, were restricted to 251 for seven to hand West Indies an unstoppable 3-0 lead in the seven-match series.
Zimbabwe never had a chance once Edwards removed opening batsmen Piet Rinke and skipper Terrence Duffin for ducks in the space of four balls in the first over.
Elton Chigumbura and Vusimuzi Sibanda took the opportunity to enhance their reputations with meaningful half-centuries that were the backbone of the visitors' innings before Edwards and Tino Best, respectively, removed them.
Chigumbura hit four fours and three sixes in 60 at a run-a-ball and Sibanda supported with nine boundaries in 52 from 73 deliveries. Led by half-centuries from Shivnarine Chanderpaul, Runako Morton, and Brian Lara, West Indies, choosing to bat on a hard, true pitch under sunny skies, totalled 333 for six from their allocation of 50 overs.
Chanderpaul, playing in his first match on home soil since resigning the West Indies captaincy, won tumultuous applause when he arrived at the wicket and entertained the near capacity crowd with nine fours and three sixes in 93 from 82 balls.
He gained support from Morton, who struck nine fours and one six in 79 from 82 balls, and skipper Lara, who collected nine fours in 56 from 45 balls, to get the ball rolling in the early part of the innings.
Edwards then struck with the first ball of the chase, when he had Rinke comprehensively beaten and bowled for pace, and Duffin caught behind touching a rising ball angled across him.
Justice Chibhabha, who has emerged as a player for the future for Zimbabwe on this trip, and Brendon Taylor added 55 for the third wicket to settle the nerves of the visitors.
They were just beginning to get into the swing of things, when Taylor was adjudged lbw to Dwayne Smith for 26 in the 12th over.
This was another setback that Zimbabwe could ill-afford, and though Chibhabha, Chigumbura, and Sibanda all carried the fight to the West Indies attack, the visitors found the mountain to steep to climb.
Earlier, Chanderpaul added a vital 83 for the fourth wicket with compatriot Ramnaresh Sarwan, who got 40, before he was the last batsman dismissed in the 48th over bowled by Edward Rainsford.
Morton and Lara had paved the way for the later batsmen with some early ball-beating in a second wicket stand of 109 from 122 balls, after newcomer Sewnarine Chattergoon was run out for nine in the eighth over.
Lara was caught behind off Tawanda Mupariwa in the 22nd over and Morton was caught at long-off off Prosper Utseya to leave West Indies 166 for three.
This brought Sarwan to the wicket and he consolidated West Indies' position with Chanderpaul before he was caught at long-on off Rinke in the 41st over.
The wicket of Marlon Samuels, bowled by Chibhabha for nine in the 46th over, slowed the West Indies down, but Chanderpaul blossomed late and helped to beef up the total before his dismissal.
West Indies also won the first two matches last weekend by five wickets and 98 runs at the Antigua Recreation Ground, but the third match scheduled for Saturday here was cancelled because of rain.
The series continues on Wednesday, when the two sides contest the first day/night ODI in the Caribbean at St. Lucia's Beausejour Stadium, followed by back-to-back matches next weekend at Trinidad et Tobago's Queen's Park Oval.