Hardy utilised a range of skills including knees, elbows and strikes to overcome a slow start.
Sadollah was effective in the opening round, fighting inside and sticking to his favoured clinch game.
The 'Outlaw' Hardy stepped things up in the second and surprised Sadollah with a succession of successful takedown attempts.
Hardy was relentless in the final round and opened a nasty cut over his opponent's eye to assure victory.
All three judges gave the win to Hardy, with the scorecards reading 29-28 30-27 29-28 in favour of the British fighter.
Victory in the co-main event on home soil earned Hardy his second consecutive win since making his comeback in the welterweight division.