Liam Bridcutt twice turned the ball into his own net on Sunday, the first coming just before half-time, after Kazenga LuaLua had levelled Martin Skrtel's early header proving crucial.
Lewis Dunk also scored an own goal, although Reds boss Kenny Dalglish will be more pleased that man-of-the-match Andy Carroll was also on target before setting up Luis Suarez, who had already missed a penalty he was urged to take by his gaffer.
It was a good day all round for Liverpool, so much so that Jamie Carragher could even have a joke with a male streaker, who entered the playing area in stoppage time.
For, after six barren seasons, Liverpool now have the familiar scent of silverware in their nostrils.
Whilst the financiers might place a Champions League berth at the top of their list of targets over the remaining weeks, for supporters, days out at Wembley are special.
In seven days' time, Kenny Dalglish will lead his team into a Carling Cup final confrontation with Cardiff.
It could turn out to be the first leg of a double.
Dalglish could not have wished for a better start today. Distracted by the presence of the excellent Carroll, who was wrestled to a standstill by Adam El-Abd, Brighton allowed Skrtel a free run at Steven Gerrard's near-post cross. The header was firm enough to send it whistling past Peter Brezovan.
Brighton were fortunate to escape when they fell asleep at a quickly-taken free-kick, allowing Gerrard to shoot narrowly wide.
The visitors were being so comprehensively outplayed that it came as something of a surprise that they levelled, with LuaLua - teed up by a training ground free-kick routine - expertly finding the bottom corner from 25 yards with a low shot.
The injection of confidence was clear, triggering an open contest.
Carroll nodded a Gerrard cross over, Inigo Calderon superbly cleared off the line to deny Suarez and Gerrard's free-kick was tipped over by Brezovan.
In return, the speedy Lua Lua flashed a shot into the side-netting after he had scorched past Glen Johnson.
After all that, Liverpool's second goal was scrappy.
Suarez, booed by the Brighton fans even though their manager Gustavo Poyet had backed his fellow countryman in the recent racism row on plenty of occasions, produced some neat trickery to create a shooting opportunity for himself.
Brezovan was equal to it but when the rebound bounced kindly for Johnson, the full-back turned his header goalwards. Sam Vokes thought he had cleared, only for the ball to strike Bridcutt at point blank range and bounce back into the net.
Within 10 minutes of the restart, Jordan Henderson nearly turned home an off-target Gerrard shot and Brezovan denied Downing.
When Downing cut a cross back for Carroll, the burly striker swept home first time from 10 yards. It was no more than the big Geordie deserved - fit and firing, his size provides a threat no defence will find easy to contain.
Brighton failed to manage it and with three goals in his last 10 appearances, Carroll is beginning to find the form which brought him such prominence at Newcastle.
The visitors' nightmare was not over though.
First Bridcutt was in the wrong place at the wrong time again as Gerrard's low cross bounced off him at the near post to provide Liverpool with a second own goal.
Then Dunk joined in the act. After succeeding only in kneeing the ball towards his own goal as he tried to juggle and clear, Dunk deserved to be punished for sheer stupidity - although there was some doubt as to whether it crossed the line.
After substitute Dirk Kuyt had been felled 10 minutes from time, the party atmosphere demanded Suarez take the spot-kick .
In keeping with the slapstick, he missed, only to atone from Carroll's nod down shortly afterwards to emphatically stamp Liverpool's presence in the last eight, where they will host Stoke.
