The former Coventry City player kept the Blues on top of the table with his first hat-trick for the St. Andrew's club.
They were opportune goals in as much that Preston, one of Birmingham's main rivals for promotion, had previously subjected the home side to relentless pressure with Nugent and Brett Ormerod in particular proving extremely troublesome.
McSheffrey was undoubtedly the architect of Birmingham's success but it was achieved after many anxious moments when their defence was far from secure early and late in the game.
There was absolute commitment from Preston intent on making amends for their 2-0 defeat at Luton but Birmingham, more by luck, held out to maintain their position as league leaders as the result was hardly a fair reflection of Preston's performance.
Birmingham rode their luck after being in trouble in the early stages when they enjoyed something of a charmed life. Under-pressure Radhi Jaidi could only put the ball into the path of Brett Ormerod and his shot cannoned back off Maik Taylor to Nugent who watched his cross-shot bounce wide after hitting the base of the post.
Encouraged by this positive start Preston continued to embarrass Birmingham's defence and Nugent slipped through to clip a shot over the bar.
Simon Whaley then went close with Birmingham's rearguard ball watching and only a fine save by Taylor prevented Ormerod scoring with a shot on the turn.
The response from Birmingham came from Matthew Upson when his header from a McSheffrey corner was bustled off the line by Chris Sedgwick.
This incident was quickly followed by a strong penalty appeal after McSheffrey was tripped by Liam Chilvers as the little winger was cutting across the penalty area.
If anything the failure of the referee to award a spot-kick only spurred McSheffrey to greater effort which resulted in him lifting Birmingham with the opening goal after 32 minutes.
A low pass from Mat Sadler found Cameron Jerome who turned quickly to switch the ball into the path of McSheffrey who scored following a slight deflection.
McSheffrey was now on fire and Preston were made to rue Chilvers' reckless tackle and the former Coventry player displayed his goalscoring flair in the 39th minute when he collected another through pass from Sadler to effectively destroy Preston when he coolly slotted a low shot past Carlo Nash.
All the good work was wasted a minute before half-time when Taylor failed to punch away Paul McKenna's corner and live-wire Ormerod was on hand to snatch his third goal of the season.
Preston strived for an equaliser and applied relentless pressure with Matt Hill going close to what would have been a fully deserved equaliser.
But three minutes from time the persistent McSheffrey earned his belated penalty when he was brought down by Sean St Ledger and promptly converted the spot kick.