Gabriel Jesus scored the only goal of the game as City made it 22 wins from the last 23 games.
City started brightly and were ahead after just four minutes when Jesus nodded home close range after Kevin De Bruyne’s superb ball into the box, a dream start for a side who made seven changes to the starting XI that beat Cardiff in midweek.
The early goal settled us and we proceeded to dominate possession for much of the first half, prodding and probing the Brighton defence, but we lacked our usual brilliance in the final third and struggled to create clear-cut chances.
Kyle Walker was perhaps fortunate to get away with just a yellow card after clashing with Alireza Jahanbakhsh off the ball. The Video Assistant Referee reviewed the initial decision and was satisfied a booking was sufficient punishment.
Brighton produced fleeting moments of quality on the break, particularly Anthony Knockaert whose quick feet and direct style was given City’s backline something to think about. His effort that flashed over the bar from distance was perhaps their best moment of a dull first half.
The second half was far more vibrant. Brighton began the stronger and were unlucky not to equalise when Shane Duffy's header was cleared from underneath his own crossbar by Aymeric Laporte.
Raheem Sterling's effort from distance was palmed away by Matthew Ryan, before substitute Jose Izquierdo forced a comfortable save from Ederson as Brighton went in search of an equaliser.
City could have made 2-0 but for Ryan's save from Sterling after a rapid counter-attack with seconds remaining.
It was harder work than perhaps it should have been but City are coming back to Wembley for another showpiece final.
Man of the Match: Aymeric Laporte
We may have failed to produce our usual free-flowing football, but we were resolute at the back. Laporte, outstanding all season, was the man who marshalled the backline and he did it superbly. He also won some vital headers in the final moments as Brighton went direct in a bid to find a way into the game.
Bernardo also deserves a mention. Tireless as ever.
What it means
City are into the FA Cup final for the first time since 2013 where we will play the winner of tomorrow’s other semi-final between Watford and Wolves.
It also keeps alive our hopes of an unprecedented Quadruple. Never in the history of English football has a side won all four major trophies, but City, with the Carabao Cup already in the bag, remain on course to do it.
We could potentially play 12 more matches this season. Win them all and significant history will be made.
Guardiola has played down the prospect, but if City keep winning – and this was our 14th victory in succession and 22nd in our last 23 matches - he may have to revise his position.
Pinpoint De Bruyne
He’s been sorely missed.
Kevin De Bruyne, City’s best player last season, has only featured 26 times in what’s been an injury-hit campaign this time around.
But he’s now fully fit and back to his best. After a superb display against Cardiff on Wednesday, he showed once again what City have been missing when, with just four minutes on the clock, he produced a pass of pinpoint accuracy to give Gabriel Jesus the simple task of nodding City in front.
Few players have the ability he has to make chances for others. Keep him fit, and our chances of more silverware before the end of the season increase greatly.
The City squad and backroom staff will now stay in London ahead of Tuesday’s Champions League quarter-final first leg against Tottenham Hotspur.
Spurs will be hosting a game at their new Tottenham Hotspur Stadium for only the second time. It’s a wonderful, imposing arena and the fans created a superb atmosphere in the 2-0 win over Crystal Palace on Wednesday.
City will have to silence the crowd and figure out a way to beat one of the finest attacking sides in the game.
That’s followed by a trip to Crystal Palace next Sunday – the first of our final six Premier League games.