The victory matched the competition’s record final win — set when Bury beat Derby County 116 years ago — and was the perfect end to an amazing season for unarguably one of the finest teams to grace the long history of the English game.
Coming after they retained the Premier League title last week and won the League Cup in a penalty shootout over Chelsea, City’s sixth FA Cup triumph made them the eighth team to win the prized League and FA Cup double and first since Chelsea in 2010.
Raheem Sterling was initially credited with a hat-trick, only for his first goal to later be awarded to Gabriel Jesus, who also got two as City ended their 61-game season with 169 goals, beating their own previous best of 156.
“It was an incredible final for us and we have finished an incredible year,” City manager Pep Guardiola said. “The players deserve all the recognition. To have gone 10 months in all competitions and be the first team to do that is incredible.”
City, 2-0 up at halftime through David Silva and Jesus, effectively sealed the deal when Kevin de Bruyne came off the bench to smash in the third after 61 minutes.
Jesus slotted the fourth before Sterling, who was brought up in the shadow of the stadium, took centre stage with two in the last 10 minutes.
“I grew up here and saw this stadium get built. It’s a massive dream come true to win trophies here,” said the England winger.
“It shows what the manager is building here. He said we needed to get the mentality right and we did that and did it exceptionally well.”
Other than one early chance for Roberto Pereyra, Watford never looked remotely capable of ending their 30-year winless run against City in their second appearance in the final having lost to Everton in 1984.
“We knew we had to play the perfect game and started well but they were better, congratulations to them,” said Watford coach Javi Gracia, whose team finished 11th in the league, 48 points behind the champions.
It always looked a long shot for them to deliver a classic Cup upset. City had beaten Watford in the teams’ last 10 meetings, scoring 32 goals in the process, while Watford’s last win in the fixture came in 1989 in the old Second Division.
The underdogs did have the first clear chance after 11 minutes when Pereyra shot from the edge of the box but Ederson flew off his line to save with his foot and that proved their high-water mark.
There was an air of inevitability when City struck after 26 minutes as diminutive duo Silva and Sterling won headers against big Watford defenders, allowing Silva to seize on the loose ball and fire past Heurelho Gomes.
They doubled the lead when Bernardo Silva supplied Jesus, starting ahead of the unused Sergio Aguero, to steer the ball goalwards.
His hooked shot looked to have crossed the line, but Sterling lashed it into the net to make sure – initially being given the goal before the FA changed its mind an hour after the match.
Following a brief attacking flurry at the start of the second half, Watford’s hope was extinguished when City broke at pace and De Bruyne drilled in the third five minutes after coming off on to the pitch.
Watford, too late, threw men forward and were exposed when Jesus broke from his own half to tuck in the fourth. Bernardo Silva was the provider again as Sterling arrived at the back post to smash in the fifth and the local boy fittingly finished things off three minutes from time.
After also winning the Premier League and League Cup last season, City have now lifted five of the past six available domestic trophies.
The one blip is their failure to again make even the semi-finals of the Champions League – something that will nag at Guardiola throughout the summer but ensure he and his team come back full of vigour in August.
“What a team this is,” said Bernardo Silva. “Now it is time to rest, to celebrate and next season we will try and win it all again.”
Also celebrating on Saturday were Wolverhampton Wanderers, who will now qualify for the Europa league via their seventh-place finish in the Premier League.