Recently back from a loan spell at Millwall, Jamie, 21, entered the fray for Kevin-Prince Boateng with 13 minutes remaining and the match finely balanced at 0-0.
It took less than a minute for his first contribution, a cross-field pass into the path of Jermain Defoe, who controlled and lifted a tricky chance over David James but over the bar.
Then, two minutes later, Jamie's most telling contribution as he led a counter-attack from the left and carried the ball some distance before picking out Aaron Lennon on the right, Aaron's cross turned home for the winner by Dimitar Berbatov.
"It was his debut and he had 15 very good minutes," said Head Coach Juande. "He understood perfectly what I asked of him when he came on.
"He played very well and I'm very happy with him."
Juande Ramos was impressed with Jamie O'Hara's cameo role at Portsmouth as the young midfielder made an impact on his debut at Fratton Park.