With the Lions bowled out for 178 in their second innings, the Cobras romped to a second consecutive four-day title with an innings-and-165-run win.
It was the Cobras’ 10th trophy of the franchise era, and their seventh in the last four years.
The Lions had gone into the final day on 124 for five, still 220 runs short of making the Cobras bat again, and lost Rassie van der Dussen (55) to the fourth ball of the day.
After Sizwe Masondo (22) and Cliffe Deacon (24 not out) had held up the Cobras for the next 20 overs, Travis Muller claimed two wickets in two balls to break the last piece of Lions resistance.
Piedt then picked up the final two wickets to take his season tally to 45 in eight matches and finish as the leading wicket-taker in the tournament.
The Cobras also had the two leading run-scorers in the competition in Stiaan van Zyl (933) and captain Justin Ontong (927).