The leg spinner was brought into the side for the final Test of the series, handed his chance with the tourists having been without a wrist spinner since Liam Livingstone suffered a knee injury in the first Test in Rawalpindi.
England finished the opening day on seven for one after Zak Crawley was out for a duck, but it was a day which belonged to the debutant as Ahmed, England's youngest ever men's Test cricketer, finished with two wickets for 89 runs across three spells.
England have already wrapped up the series following victories in Rawalpindi and Multan, but that did not take away from the magnitude of the occasion for Ahmed.
"I didn't expect to play. I just came on this tour to get better, but they've given me a chance to play," Ahmed said after the day's play.
"I didn't sleep at all last night. I was very nervous before the first ball, but the whole day was good."
Ahmed's first wicket came when he cleverly set up Saud Shakeel before the Pakistan batter was caught by Ollie Pope at short leg.
It was a first glimpse of the talent spoken about by captain Ben Stokes and head coach Brendon McCullum as he first beat Saud with a googly turning past the bat before following it up with a wicket-taking leg spinner that just took the edge.
Ahmed's second scalp came in the evening session when Faheem Ashraf was trapped lbw for just four, with DRS upholding the decision following a review to leave Pakistan on 237 for seven.
Reflecting on the day as a whole, Ahmed added: "I rushed a little bit in that first spell, but Stokesy didn't care about runs, he just wanted wickets.
"I've bowled at left-handers all my life as my brother's left-handed and I used the tactic I used against him. Googly then leg spinner and it worked."
Ahmed's day started with being awarded his Test cap by Nasser Hussain before he received a warm hug from his father Naeem, who was permitted to join the team huddle.
"Probably the best day of my life, probably the best moment (receiving his cap from Hussain with his father there)," he said. "He's worked really hard with me throughout my life."
England have been on an upward trajectory, winning eight of their last nine Test matches heading into this contest, and Ahmed was delighted to come into a team riding the crest of a wave.
"I mean I think it's the best Test team that's ever played, so it's great to be part of it," he said.
Pakistan coach Saqlain Mushtaq, who played 49 Tests as an off-spinner, was full of praise for Ahmed, saying: "I really like his control and the most important thing is his confidence.
"The first game, the way he started his first over, he showed the first ball was a wrong-un one and that was brilliant.
"A young chap, just 18 years old and the first ball he's doing is a wrong-un one and that shows that he has a lot of potential. He looks a really good prospect for the England team in the future."