John Terry, who will leave the club at the end of the season after more than two decades, made his first league start since September’s 2-2 draw with Swansea City and opened the scoring after 22 minutes.
However, two minutes later Watford scored the equalizer courtesy Etienne Capou.
Just before half time, Cesar Azpilicueta restored Chelsea’s lead and it seemed when contest would soon end when Michy Batshuayi added a third just after the break in the 49th minute.
However, Watford’s Daryl Janmaat and Stefano Okaka brought it back to 3-3 with successive goals in 51st and 74th minute respectively, reports goal.com.
However, the Antonio Conte side were able to take the acclaim on a lap of honour when substitute Cesc Fabregas struck from the edge of the area with three minutes left before the end of the game.