Juergen Klopp’s side, who have lost just once in the league all season, have 88 points, a club record in the Premier League era.
Manchester City, who beat Tottenham Hotspur 1-0 on Saturday, are on 86 but have a game in hand.
That extra game for Manchester City will be played on Wednesday when Pep Guardiola’s side travel to Old Trafford to face Manchester United.
Now the champions will make the short trip with the pressure firmly back on.
Against a Cardiff side battling for Premier League survival, it was a confident, patient performance from Liverpool who have now enjoyed nine straight wins in all competitions.
“It was prepared to be a proper banana skin and we knew that, the boys were unbelievable. It was clear, difficult for all of us,” said Klopp.
“The boys tried really with all they have, we only speak about the things we have to do.”
“Their attitude is outstanding and it’s a tough season but a very positive one as well,” added the German.
Cardiff defended deep and in numbers and limited Liverpool’s opportunities, but Roberto Firmino missed a great chance to open the scoring in the 22nd minute.
He found himself one-on-one with goalkeeper Neil Etheridge but lifted the ball over the bar.
Etheridge was then quick off his line to save with his legs from Mohamed Salah, while Cardiff offered a warning when Alisson Becker tipped over Oumar Niasse’s close-range effort.
After an intense spell of pressure following the interval, Georginio Wijnaldum broke the deadlock for Liverpool in fine style with a first-time strike.
It came from a clever short corner kick from Trent Alexander-Arnold.
Sean Morrison then missed a golden opportunity for Cardiff to equalise, making a hash of a header when he had an open goal at his mercy after Alisson misjudged a cross.
Late in the game, Morrison was judged to have pulled down Mohamed Salah in the box.
Substitute James Milner converted the 81st minute penalty kick to make sure of the crucial three points for Klopp’s side.
Liverpool’s ability to avoid slip-ups against lowly opposition has been a key part of their season.
They have taken 52 points from a possible 54 against teams in the bottom half of the table.