Jason Roy and captain Joe Root both smashed centuries as the tourists easily reached their target of 361 with eight balls to spare in Barbados.
It was their highest ever run-chase in the format.
Chris Gayle's innings of 139 off 129 balls went in vain as the Windies' poor form in ODI cricket continued.
The second encounter of the five-match series will be played on Friday.
Man City beat Chelsea 1-0 to win FA Cup
Manchester City won the FA Cup on Saturday, beating Chelsea 1-0 in the final with a deftly finished 72nd-minute goal from Antoine Semenyo to complete an English cup double.
Kane grabs hat-trick as champions Bayern crush Cologne
Bundesliga top scorer Harry Kane scored a hat-trick to guide champions Bayern Munich to a 5-1 demolition of visitors Cologne in the league finale on Saturday.
Sinner beats Medvedev to set up Italian Open final with Ruud
World number one Jannik Sinner had a restless night before completing a rain-interrupted victory over Daniil Medvedev to reach the Italian Open final on home soil on Saturday.
Celtic snatch title from Hearts with last-gasp victory on final day
Celtic scored two late goals to beat Heart of Midlothian 3-1 at home in a nerve-racking final-day title showdown to be crowned Scottish champions for a record 56th time on Saturday.
Kohli to play 2027 World Cup only if he can add value
India veteran Virat Kohli said he has nothing left to prove and would consider playing the 2027 One-Day International World Cup only if he can still contribute meaningfully.
