Malky Mackay's Cardiff had only won one of their last five games before the clash with Rovers at the City Stadium, but goals by Fraizer Campbell and Joe Mason either side of half-time and Peter Whittingham's injury-time penalty ended their dip in form and moved them further ahead of second-placed Hull, who play Watford on Tuesday.
The win keeps Cardiff in pole position to secure automatic promotion to the Barclays Premier League as champions with seven games remaining. The result meant Blackburn, who were relegated from the top flight last season, slipped into 19th place and only above the bottom three on goal difference.
Barnsley moved away from danger thanks to their 2-0 win over Leicester at Oakwell. Michael Keane's fourth-minute own goal and Chris O'Grady's 40th-minute strike saw the Tykes climb into 20th place.
The defeat continued Leicester's woefully inconsistent form and saw them remain just out of the top six, with sixth-placed Brighton still to play Charlton on Tuesday. Barnsley's win also meant Huddersfield find themselves in the relegation zone before they kick off against Bolton on Tuesday.
Wolves gave their hopes of avoiding the drop a shot in the arm with a 3-2 win over local rivals Birmingham at St Andrew's. Stephen Hunt found the net from inside the six-yard box in the 20th minute before two goals by Sylvan Ebanks-Blake, one from the penalty spot, saw Wolves take a three-goal lead at half-time.
After the break, Wade Elliott inspired a Birmingham fightback by scoring one penalty and netting the rebound after another was saved, but it was not enough as Dean Saunders' side held on for a vital win.
Elsewhere, Sam Baldock scored an injury-time equaliser for Bristol City as they drew 1-1 against fellow strugglers Sheffield Wednesday at Ashton Gate. Baldock cancelled out Jermaine Johnson's first-half strike in the second minute of injury time to leave Bristol City seven points adrift of safety, with Wednesday just above the drop zone.
Matt Phillips' late goal saw 10-man Blackpool defeat promotion-hunting Crystal Palace 1-0 at Bloomfield Road. Phillips fired into the top corner from Tom Ince's pass to earn the Seasiders a late win after Barry Ferguson was sent off close to the end of the first half for his second bookable offence.
Lewis McGugan's last-gasp penalty salvaged a point for fifth-placed Nottingham Forest in a 1-1 draw at Burnley. Burnley has taken the lead in the second half
through a deflected shot from Junior Stanislas. Millwall and Ipswich played out a goalless draw at The Den.