The win for Rangers denied Dunfermline their first home victory of the campaign in the Scottish Premier League.
McCulloch played as a striker earlier in his career and delivered the goods after starting up front at East End Park, as Daniel Cousin - set for a return to Ibrox - looked on from the stand.
McCulloch struck after David Healy cancelled out Andy Kirk's shock opener and Sone Aluko and Salim Kerkar then added a goal apiece in the second half to earn Rangers all three points.
Rangers made one change from the side who crashed out of the William Hill Scottish Cup to Dundee United last week for the clash with the Pars.
Mervan Celik - who lasted just 45 minutes of his first start - was dropped to the bench and McCulloch was drafted into the starting line-up.
Dunfermline were without on loan Rangers midfielder Kyle Hutton, while Iain Turner failed to recover from injury meaning Chris Smith was again in goal.
It was McCulloch who had the first real chance when he collected from Healy and saw an early effort from close range blocked.
But the home side could have taken the lead when David Graham burst through on goal only to see his shot crash off the post, before Liam Buchanan's rebound effort was blocked by goalkeeper Allan McGregor.
Dunfermline were celebrating with 16 minutes gone though when Paddy Boyle's deep cross from the left found Kirk at the back post and he slotted home.
Rangers were back on level terms within eight minutes when Maurice Edu saw his shot blocked by the goalkeeper after a one-two with McCulloch, and Healy pounced to rifle the loose ball into the back of the net.
The Scottish champions were threatening again when skipper Steven Davis had a go and his shot bounced onto the crossbar and over.
The visitors continued to press for a second goal and a Davis corner eventually broke for Carlos Bocanegra but his volley was well off target.
The pressure paid off after 39 minutes when a Davis free-kick found Bocanegra and he teed up the shot for McCulloch to lash home his first goal of the season.
McCulloch could have added to his tally shortly after the restart when he met a Healy cross and nodded just over.
Rangers made a double change with just over an hour gone when Kirk Broadfoot - back from injury - and Celik were thrown into the action for Kyle Bartley and Healy.
Rangers increased their lead further after 70 minutes when Aluko raced onto a pass from McCulloch and sent an unstoppable left-foot shot into the top corner from 25 yards.
The winger then came to the rescue at the other end when he cleared an Alex Keddie header off the line.
Celik could have added his own name to the scoresheet with a swerving effort that dipped just over the crossbar.
It was another substitute, Kerkar, who had the final say when he dispatched a low shot past Smith with five minutes to go after a couple of minutes on the park.