Sri Lanka qualified for the ICC World Cup 2019 after West Indies lost the opening ODI of the five-match series against England on 19 September.
Earlier, Jonny Bairstow smashed his maiden ODI century, hitting 100 not out off 97 balls to lead England to an easy seven-wicket win against Windies at the Old Trafford.
The win not only put England 1-0 up in the series, but also ended Windies' hopes of earning direct qualification for the ICC Cricket World Cup 2019, that will also be held in the United Kingdom.
With September 30 set as the cut-off date for automatic qualification for the ICC's pinnacle 50-over tournament, the Windies (78 points) now cannot move ahead of Sri Lanka (86 points) on the ICC ODI Team Rankings irrespective of how their remaining matches against England pan out.
This means the 1996 world champions have become the eighth and last team to qualify directly, joining Australia, Bangladesh, England, India, New Zealand, Pakistan and South Africa.
A relieved Sri Lanka's ODI captain Upul Tharanga said: "It's no secret that we (Sri Lanka) have been going through a tough time, but I want to say a big, big thank you to our fans who've kept faith with us when things looked bleak.
"ICC events have always brought out the magic in Sri Lanka cricket, and I look forward to proving that once again.
"We have a clear plan toward the World Cup, and we will work hard at achieving each step. As we say in the dressing room, - Little 'w's (wins) add up to make the big 'W' (win) - so that's what we'll be focusing on and I know you will see Sri Lanka's special brand of cricket out there once again soon."
The Windies will now progress to the 10-team ICC Cricket World Cup Qualifier 2018, where they will be joined by the bottom three sides on the ICC ODI Team Rankings - Afghanistan, Zimbabwe and Ireland - as well as the top four sides from the ICC World Cricket League Championship and the top two sides from the ICC World Cricket League Division 2.
The top two sides from the World Cup Qualifier will complete the 10-team line-up for the ICC Cricket World Cup 2019, which will be staged in the United Kingdom from 30 May to 15 July.