A goal in each half was enough for Brian Little's side to beat a struggling home side that found their former keeper Gavin Ward in inspired form.
Wrexham, with a further three former Chester players in their starting line-up, struggled in the early stages as the home side forced a succession of corners which came to nothing.
City did have the ball in the net in the 21st minute when Kevin Ellison's corner curled into the net, but Chris Holroyd was adjudged to have fouled the keeper.
Within a minute, the ball was in the net at the other end as Wrexham took the lead. Paul Hall pulled away from his marker and was expertly picked out by Michael Proctor. Hall then fired a right-footed shot into the bottom corner from 12 yards out.
Ellison's shot from a tight angle forced Ward to make a smart save at his near post, and Hall fired wide narrowly before the break with a similar chance to the one he had scored from earlier.
In the 58th minute Holroyd stung the hands of Ward with a powerfully struck shot that the keeper did well to parry away.
Chester should have drawn level four minutes later when the ball broke fortuitously for Ellison who had plenty of time and space but his eight-yard effort was superbly tipped over by Ward.
Holroyd then had the ball in the net again but was adjudged to be offside, and, as in the first half when a 'goal' was chalked off, Wrexham struck almost immediately as they doubled their advantage.
A long throw was allowed to bounce in the box and Proctor volleyed the ball in over his shoulder to give John Danby no chance.
Ward denied Ellison with another fine save and Paul McManus fired narrowly past the post as Chester failed to find a way back into the game and have now been sucked into the relegation dogfight themselves.