But his 82nd-minute effort took a huge deflection off the head of centre-back David Mirfin before looping over goalkeeper Josh Lillis.
It was tough luck on Scunthorpe who had built well on their early lead. That came in the 11th minute when midfield man Michael O'Connor curled home an excellent free-kick from the edge of the box.
It was only his second goal of the season, and he went close again after a surging run with a 20-yard effort that was saved low to his right by Cardiff keeper David Marshall.
The Welshmen, looking for their first win in four games, struggled to make much impact up front in the first half. But they looked much better in the second half as they chased an equaliser.
Jay Bothroyd was denied by the legs of keeper Lillis with one close-range effort, while Michael Chopra, still looking for his first league goal since the end of September, fired another effort across the face of goal and wide of the far post.
But Scunthorpe still looked dangerous on the break and were so close to making it 2-0 when a flick from leading marksman Gary Hooper was scrambled off the line by centre-back Mark Hudson in the 79th minute.
Three minutes later Cardiff snatched the equaliser they had been threatening and substitute Ross McCormack then almost snatched a late winner with a shot that was turned away by Lillis.
Scunthorpe then had appeals for a penalty turned down in stoppage time when substitute Jonathan Forte went down in the box.