Aston Villa captain Jack Grealish scored the crucial goal as Dean Smith's team secured Premier League safety with a 1-1 draw at West Ham United.
Needing to better the result of Watford, who were behind the 17th-placed Aston Villa on goal difference ahead of the final day, Grealish broke the deadlock on 84 minutes with a curling strike past Lukasz Fabianski.
Andriy Yarmolenko responded within a minute for West Ham to set up a tense finish but Villa held on to stay up.
Watford were relegated after losing 3-2 at Arsenal. A double for Pierre-Emerick Aubameyang and Kieran Tierney's strike put the Gunners 3-0 up before Troy Deeney and Danny Welbeck scored to give the Hornets hope at Emirates Stadium.
They did their bit as Joshua King, Dominic Solanke and Junior Stanislas found the net at Goodison Park but they needed both Villa and Watford to lose.