Representatives for the 22-year-old actor, who was born in Colorado but raised in Ireland, have confirmed that he is set to wed his girlfriend of two years after recently popping the question.
Rumours that the couple were engaged began to circulate earlier this week when Madeline, also 22, was seen sporting a glittering diamond on her ring finger.
Jack and Madeline at the Irish Film and Television Awards in 2013
The Limerick-born beauty flashed the sparkler as she arrived at a studio in Dublin to work on the pilot for a TV show called Bounce.
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Jack, who starred alongside Vince Vaughn in Delivery Man and is currently filming Macbeth with Michael Fassbender and Marion Cotillard, has been inseperable from Madeline since the pair first met.
The couple made contact on Twitter, exchanging flirtatious messages that soon blossomed into romance.
The couple have been together for two years
Madeline, who Jack has previously described as the "best girlfriend ever", accompanied her beau to America last year so that they wouldn't be parted while he filmed Delivery Man.
"We had a house in LA," she said after returning from the US. "It was good that we were together and experiencing it together."
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Jack recently won an Irish TV and Film Award for What Richard Did, but the road to silver screen stardom hasn't always been smooth.
The actor revealed that he hit a low several years ago, before landing his role in Transformers: Age of Extinction.
Jack is currently filming Macbeth alongside Michael Fassbender and Mario Cotillard
"I hadn't worked in nine months," he said. "I was completely destitute. I was living at home with my mum, and she had just developed breast cancer.
"It was difficult because I have a five-year-old brother and seven-year-old sister, and we were in a dark place economically."
Since then, Jack's career has gone from strength to strength and he has been enjoying every minute.
"It's been mad," he said. "I couldn't even get an audition for network TV at home in Ireland. Now I'm talking about Vince Vaughn and Mark Wahlberg like they're my mates. It's crazy, man."