The former Cardiff City midfielder struck six minutes before half-time with a superb drilled effort into the bottom corner to settle the contest.
Partick could have grabbed an equaliser late on, with Adam Matthews clearing Stephen Lawless' header off the line, but Celtic held firm to record a seventh consecutive domestic clean sheet.
That also ensured a third straight 1-0 victory for Neil Lennon's side, leaving the champions 11 points clear at the top of the table.
Nearest rivals Motherwell consolidated second place with a comprehensive 4-0 win over St Johnstone at Fir Park.
John Sutton's header gave them a first-half lead, before Iain Vigurs doubled the advantage, pouncing on a rebound after Lionel Ainsworth's low drive.
Ainsworth then got on the scoresheet himself, before substitute James McFadden added a fourth with a curled effort late on.
Aberdeen came from behind to beat Dundee United 2-1 at Tannadice.
The hosts took a second-half lead through John Souttar, but Aberdeen were level when former United captain Barry Robson restored parity from the spot after Andrew Robertson had handled in the area.
Peter Pawlett's last-minute header completed the turnaround.
Ross County ended a 10-game winless run courtesy of a 2-1 victory over Inverness at the Caledonian Stadium.
Two goals in as many minutes from Scott Boyd and Alex Cooper gave the visitors a 2-0 first-half lead, but they were forced to hang on after Aaron Doran pulled one back - despite Inverness seeing Ross Draper sent off for an elbow on Stuart Kettlewell.
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