A free-kick in either half from Danny Guthrie condemned Blues to defeat at the Madejski Stadium.
The Royals midfielder handed the hosts the lead in the 32nd minute with a delivery from the left that evaded everybody in the Blues box to leave the net bulging at the far post.
Blues rallied after the break and looked good value for at least a share of the spoils. However, Guthrie burst the bubble when his 20-yard free-kick crept in off the left post and Blues couldn't recover.
Afterwards, Lee Clark described this match as a tale of two final thirds - Reading clinical in one, Blues not so in the other. It was an accurate description because on chances created there was little between these two teams and the visitors even had the lion's share in the second-half.
Both goalkeepers' fingers were stinging in quick succession around the quarter-of-an-hour mark. Darren Randolph on hand to deny Pavel Pogrebnyak an almost certain goal but Alex McCarthy blocked out Chris Burke's effort.
Adam Le Fondre sparked a nervy moment in the Blues goalmouth just before the half-an-hour mark when Dan Burn struggled to get the forward's pass clear from the six yard box but Randolph was quick to smother with Hal Robson-Kanu lurking.
Then came the first of Guthrie's double. A free-kick went against Burke for handball out on the left flank and the former Liverpool man swept in a dangerous delivery that found the far corner.
Reading could have doubled their lead almost immediately. Le Fondre outpacing Burn only to be distracted by the outrushing Randolph as his shot sailed high and wide.
Blues managed to force McCarthy into another save before the break when Jesse Lingard teed up Tom Adeyemi for a thumping shot from 25-yards.
The away side started the second-half brightly and David Murphy's cross from the left found Burke on the right side of the area in the 59th minute but the Scotland international's shot fizzed over the bar.
The lively Garath McCleary almost watched his low 18-yard drive creep into the left corner only for Randolph to make an outstanding save.
Fit-again Nikola Zigic entered the fray in the 68th minute for his first taste of action this season and he almost made an immediate impact. Murphy's delivery picking out the giant striker's head but he couldn't keep his effort down. It was further evidence of Blues cranking things up a gear in search of an equaliser but then came a sucker punch with Gunthrie's second.
The 26-year-old's strike beating the outstretched arm of Randolph to agonizingly creep in off the post and leave Blues with a steeper mountain to climb.
Another Blues sub, Wade Elliott, forced McCarthy into a save with an effort from distance but the visitors couldn't punish Reading with the resulting corner.