Championship Wrap: Cherries roar to top
Eddie Howe's team have been the surprise package in the second tier this season, and have now extended their unbeaten run in the league to 11 matches.
They were ahead in the very first minute through Matt Ritchie, with Harry Arter adding a second two minutes before the interval.
The two sides traded further goals in first-half stoppage time, Kenwyne Jones striking for the visitors before Marc Pugh restored Bournemouth's two-goal advantage.
Two Sean Morrison goals for Cardiff came either side of Yann Kermorgant's stunning free-kick for the hosts, who were assured of victory when Callum Wilson rounded off an entertaining clash with a minute to go.
The win sends Bournemouth top of the table on goals scored, just above Middlesbrough, who defeated previous leaders Derby County 2-0 in the early kick-off to briefly rise to the summit themselves.
Former Derby man Patrick Bamford struck in the sixth minute and, when Ryan Shotton was sent off for a foul on Bamford inside the area shortly after the hour, Grant Leadbitter smashed home the penalty to make it eight games without defeat for Boro.
Malky Mackay returned to former club Watford with new employers Wigan Athletic, but it was the home side who had the last laugh as Troy Deeney's brace earned them a 2-1 victory.
Watford remain in the top six, just behind Brentford - who defeated Blackburn Rovers 3-1 at Griffin Park - and Ipswich Town, who were held to a goalless draw at Bolton Wanderers.
Eidur Gudjohnsen came on as a second-half substitute at the Macron Stadium - his first appearance for Bolton in 14 years.
At St Andrews, Birmingham City's resurgence under Gary Rowett continued as they dispatched Reading 6-1.
Demarai Gray claimed a hat-trick, while Paul Caddis, David Cotterill and Andrew Shinnie also netted for the hosts, who have now taken 14 points from Rowett's seven games at the helm.
There was a similarly comprehensive victory at Carrow Road as Norwich City hammered 10-man Huddersfield Town 5-0, while Wolves edged past Sheffield Wednesday 1-0 thanks to Leon Clarke's late winner against his former club.
Elsewhere, Charlton Athletic drew 2-2 with bottom club Blackpool, Fulham defeated Leeds United 1-0 and the game between Rotherham United and Nottingham Forest ended goalless.