The town teenagers enjoyed the upper hand earlier in the campaign during the season’s first meeting between the sides.
However, Lurgan broke the deadlock on the way to victory and the derby plaudits.
Lurgan pushed clear by 12-0 before Portadown posted a first score.
Good rucking and phase play pushed Portadown towards the Lurgan line and Ryan Neill found a way over for 12-5.
A converted try placed Lurgan with a 19-5 lead but Portadown continued to battle.
A reward arrived when Ethan Williamson raced home to cut the gap to 19-10.
It was 19-17 but Lurgan worked hard to protect the slender edge.
Congratulations go to Lyn Steele of Battlehill Road in Richhill - the winner of the Ulster Rugby family ticket following a ‘Times’ competition.