Successive defeats had left the Royals in danger of dropping out of the play-off places but Saturday's defeat of Cardiff made it two home wins in a matter of days.
Buoyed by their midweek success against Fulham, Reading took the lead in the 42nd minute when John Swift finished from Garath McCleary's backheel.
Joe Ralls equalised for Cardiff from the penalty spot on the stroke of half-time but Yann Kermorgant's free-kick on the hour mark secured three crucial points for Reading.
Barnsley shrugged off the loss of James Bree and Conor Hourihane to Aston Villa to make it two wins over Yorkshire rivals in a week and move to within a point of the top six.
Seven days after coming from behind to beat Leeds, Barnsley earned a 1-0 victory over rock-bottom Rotherham courtesy of Adam Armstrong's 70th-minute strike.
Norwich are firmly back in the mix for a play-off place after making it back-to-back wins for the first time since October.
Birmingham, without a win since Gianfranco Zola took over in mid-December, were the visitors to Carrow Road and first-half goals from Cameron Jerome and Timm Klose continued their wretched form.
The 2-0 success left Norwich two points behind sixth-placed Sheffield Wednesday, who have a game in hand.
Burton put the speculation surrounding manager Nigel Clough to one side to boost their survival hopes with a 2-1 victory at QPR.
Former Nottingham Forest player Clough was this week approached by the club over the vacant managerial position at the City Ground.
But Burton gave him a reason to stay as they moved out of the relegation zone thanks to goals from Luke Murphy - his first for the club - and Lloyd Dyer.
Conor Washington got one back for QPR but they could not force an equaliser as they suffered only their second defeat in six games.
In Saturday's other game, Jordan Hugill scored a late equaliser to earn Preston a 1-1 draw after Tom Lawrence had given Ipswich an early lead with his sixth goal in as many games
Source : PA