He has played around 170 games for Walsall and Accrington where he was on loan for a spell.
Gerrard is the second centre half Dave Jones has signed inside 24 hours. Both he and Mark Hudson, who came from Charlton, will compete with Gabor Gyepes for the defensive positions next season.
The fee is thought to be around £200,000. Similar to what Scunthorpe offered but Gerrard opted to come to Cardiff. Ironically if he gets a place in the side for the start of the season he'll face Scunthorpe in the open League game at the Cardiff City Stadium.
A busy week at City could get busier with Paul Quinn strongly linked to be arriving this weekend. The Motherwell full back did not feature in last night's shock home defeat for Motherwell by Andy Legg's Llanelli in the Europa Cup.
Should Quinn come in then Jones must surely look to shift a full back out of the door with Capaldi and Commingues the likely departees.
With the defence all but sorted now Jones can look towards improving the midfield.