The Argentinian defender played a part in the build-up and finished with a powerful header past David Marshall in the 18th minute for the only goal of the game.
Cardiff went on to dominate for long spells but could not find a way through, and Chris Hughton's men, who finished with 10 men following the dismissal of Alan Smith at the death, held on to move two points clear at the summit.
City made two changes to their line-up, with Jay Bothroyd fit to return in attack and Paul Quinn coming into defence.
Hughton, Championship manager of the month for August, made only one change to his side, with Coloccini coming in at the heart of his back four.
The Magpies dominated the opening exchanges and took the lead from the first real chance of the game.
Ryan Taylor's corner was not dealt with by the City defence and the ball was prodded back to Taylor by Coloccini. Taylor took his time with his cross and picked out Coloccini, who headed powerfully past Marshall.
The home side spurned a good chance to equalise after 27 minutes when former Magpies forward Michael Chopra beat the offside trap and played the ball across to Gavin Rae, but the presence of centre-back Steven Taylor caused the Scot to balloon his shot over the crossbar from six yards.
The Bluebirds went on to boss the remainder of the half but could not create any clear-cut opportunities.
Cardiff started the second half in the same vein, Chopra racing away down the left and playing the ball across for Bothroyd to run onto. Goalkeeper Steve Harper was alert, though, and smothered the ball at the striker's feet.
Chris Burke tested Harper with a low drive in the 69th minute as Dave Jones' side stepped up the pressure backed by vociferous support at the Cardiff City Stadium.
Burke sent over a swirling free-kick, which Bothroyd nodded wide, shortly afterwards, while there were strong appeals for a penalty in the 82nd minute when Chopra sent a shot against the outstretched arm of Steven Taylor.
Chopra should have done better with a free header four minutes from time but his effort flew well wide.
Smith, who had earlier been booked, was shown a second yellow card in injury time when he brought down Bothroyd on the edge of the box, but it was too late for Cardiff to take advantage.