Jason Bowen's extra-time winner sent Newport County into the final of the FAW Premier Cup, where they will face The New Saints. County came from behind after Lee John had given Port Talbot a 58th minute lead at Spytty Park.
But Peter Beadle's side equalised with fifteen minutes remaining after Charlie Griffin volleyed home from close range.
And then four minutes into extra-time Bowen headed home Griffin's cross to send County into the final on March 21.
Newport boss Peter Beadle:
"We've been in these situations before this season when we've dominated games and had enough chances to be a good few goals up but found ourselves 1-0 down. "And we've lost those games 1-0 so I'm delighted with the lads to show such character to come back and take it into extra-time.
"I thought our superior fitness showed and I think we deserved it in the end."
Port Talbot boss Wayne Davies:
"I thought it was a good spectacle and in fairness to Newport I think they played very well. "They created a number of good situations and but for some tremendous defending they could have gone on to win more convincingly.
"But I think the New Saints will be far too good for them in the final - they are a different kettle of fish to Port Talbot."
Newport County: Mark Ovendale, Steve Jenkins, Damon Searle, Ian Hillier, John Brough (Dean Holdsworth 70), Stuart Edwards, Jason Bowen, Lee Collier, Charlie Griffin (Nathan Davies 116), Craig Hughes, Richrad Evans.
Subs Not Used: Matthew Prosser, Tyrone Topper, Jacob Giles.
Booked: Lee Hillier, Jason Bowen.
Goals: Charlie Griffin 75, Jason Bowen 95.
Port Talbot Town: Kristian Rogers, Dylan Blain, Leigh De Vulgt, Craig Hanford, Matthew Rees, Lee Surman, Lee John, Chad Bond (Richard French 87), Tomas Wellington (Dane Williams 97), Scott Barrow, Dean Johnston.
Sub Not Used: Leon Dennis.
Booked: Leigh De Vulgt, Lee Surman.
Goal: Lee John 57.
Ref: D C Richards (Llangennech).
Att: 904.