Southampton were comfortably on top in the first 45 minutes and led through goals from Chris Baird and Bradley Wright-Phillips.
Cardiff were much improved after the break and substitute Steven Thompson pulled a goal back in the 61st minute.
Michael Chopra twice went close to equalising before Peter Whittingham denied Southampton an important win with a left-foot shot from outside the area.
The first half belonged to Southampton but the opening goal, when it came in the 30th minute, was outstanding.
Gareth Bale teed up a free-kick and Baird let fly from 30 yards with a shot which beat Neil Alexander for pace and power into the roof of the net.
Alexander was at fault for Southampton's second in the 44th minute as he failed to cling on to a header from Marek Saganowski and Wright-Phillips converted the rebound from close-range.
Cardiff manager Dave Jones sent on Thompson and within two minutes of his arrival Cardiff were a goal better off.
Whittingham crossed from the left after Baird had played him on and Thompson was left with a simple tap in from six yards.
Kelvin Davis made important saves from Chopra and Joe Ledley before Cardiff's second-half enterprise was rewarded with an equaliser.
Southampton failed to clear a cross from substitute Chris Gunter and Whittingham blasted in a left-foot shot which gave Davis no chance.
Saints had John Viafara, Saganowski and Pedro Miguel Pele all booked in a fiercely competitive match, but manager George Burley can have no complaints about the result.