The Bluebirds went a goal down at home to QPR early on thanks to Matt Smith's header but recovered by scoring two first-half goals to turn the game on its head and secure their fifth consecutive league win.
Former R's winger Junior Hoilett equalised by blocking goalkeeper Alex Smithies' attempted clearance before a header from Sol Bamba on the stroke of half-time proved enough for Neil Warnock's men, with the boss saying he was "delighted with the way we played."
Tractor Boys remain second after their first league defeat of the season
Ipswich meanwhile lost their 100% record to then-winless Fulham, with goals either side of half-time from Neeskens Kebano and Rui Fonte securing a precious away win for the Cottagers who moved to 14th.
Meanwhile Leeds United continued their unbeaten start and moved third with a 2-0 win at Nottingham Forest, as Kemar Roofe continued on from his Carabao Cup hat-trick in midweek to put the Whites in front before Ezgjan Alioski ensured the three points went back to Yorkshire late on.
The Tykes dominated the Black Cats for most of the game and coasted to victory once Iké Ugbo put them ahead, before Harvey Barnes and George Moncur piled on the misery for Simon Grayson's men, who dropped to 19th following their second consecutive league defeat.
Newly promoted Millwall stunned a Norwich side who have looked lethargic in the opening weeks of the season by going 3-0 up inside 28 minutes through Lee Gregory, George Saville and Jed Wallace before a second-half strike from Shaun Hutchinson completed the rout.
Red half of Sheffield in high spirits after another win
Sheffield United continued their impressive start with a 3-1 win over Derby County at Bramall Lane, with a Billy Sharp brace and a Johnny Russell own goal making it three wins from three at home despite Craig Bryson's late consolation.
Sharp's third and fourth goals of the season are a continuation of his form from last season when his 30 League One goals fired the Blades to the title, as manager Chris Wilder said that his side "aren't here just to make the numbers up or be the whipping boys."
Summer signing Jón Daði Böðvarsson scored his first Reading goal as Jaap Stam's men secured their first away win of the season at Birmingham City, with George Evans' late strike ensuring the points went back to London.
In the day's only score draw, substitute Jon Mason scored 31 seconds after coming on for Burton Albion to rescue a point against Sheffield Wednesday, who had gone in front on 36 minutes thanks to Gary Hooper's first league goal of the season.
Relegated Middlesbrough were held at the Riverside Stadium by Preston North End in one of the day's two goalless draws with visiting boss Alex Neil saying "if any team deserved to win it was us" after he watched his side fail to net for the third time in four games.
High-flying Wolves failed to find a way past a stubborn Brentford side at Griffin Park, leaving the Bees still searching for their first win of the season while Nuno Espírito Santo's side fell to fourth.