Nicky Law - making his first start in over a month after coming back from injury - was on hand on the hour mark to net the all-important winner when he converted from close range following Charlie Wyke's headed knock-down.
A talented Oxford side made it difficult for McCall's men at times, ensuring City could never truly relax despite their winning advantage, but the Bantams did enough to secure their third win on the spin and further strengthen their position in the top six.
McCall said: "It was another tight game for us, as a few of them have been recently, this time against a good Oxford side.
"To get the clean sheet from today (Friday), considering the attacking players they have, was huge and the goal we scored probably deserved to win the game.
"A nice bit of play from Marshy (Mark Marshall) with Jordy (Hiwula) and then the cross, the knock-down from Charlie (Wyke), and Nicky (Law) being in the right place to apply the finish.
"We'd just moved Lawsy into the number ten role at that stage, so it was a case of the four forwards combining to produce a moment of quality to get us the three points.
"They were also some strong defensive displays from us.
"(Colin) Doyley has made some good saves, Rory (McArdle) got voted Man of the Match by the sponsors, and Tony (McMahon) has got around on the cover to produce a great block in the second half.
"The noise from The Kop in the second half was fantastic - it really drove us on.
"The noises levels were exceptional, and the players really appreciated the support.
"The encouragement they got from the stands made a big difference.
"We've been managing to turn a lot of these tight games recently into wins - big, big wins - but we have to keep doing it. Sides around us have won as well.
"We will enjoy this victory because the three points are huge but we can't dwell on it too much.
"We have a big game at Sheffield United on Monday. We will be in Saturday and Sunday to prepare for this one.
"It is a game that you should really relish, and I'm sure the lads will do."