The veteran striker lifted a dour game with his fourth goal of the season to break the stalemate which was hardly riveting television viewing.
Phillips' vital goal came just 21 seconds before the end of the first half and it was the launch pad to give Birmingham a win which took them to the top of table as a result of the early kick-off.
But if Birmingham are to consolidate their promotion aspirations they will need to discover a more lethal attack than that which was on show against a spirited QPR side.
With a midfield which is struggling to get to grips with the current situation they struggled to carve out any clear-cut openings.
There is a distinct lack of creativity about the Birmingham midfield which has sadly been reflected in their recent matches.
They went into the game against QPR with only six goals from six games and it was not until 21 seconds before the end of the first period that they broke the stalemate with Phillips' close-range goal.
The goal came out of the blue with David Murphy pumping a long ball down the left.
Garry O'Connor, who was dropped from the Scotland squad in mid-week, latched on to the ball and put in a low cross which Phillips converted from close range.
Rangers, coming off the back of only one point from their previous three games, slightly had the edge but they too found it difficult to penetrate the opposition defence in which Radhi Jaidi was rock solid.
It had been expected that Rangers would adopt a more attacking style in the second half but it did not materialise as Birmingham shut down the opposition as they defended their slender advantage.
Phillips eventually made way for James McFadden, but the Scotland international had little chance to lift the game.
Birmingham's best two attempts to increase their lead came from defenders Murphy and Jaidi. Murphy shot over the bar, while Jaidi watched his downward header saved by Radek Cerny.