The 27-year-old is fighting in the main event at a show in Glenrothes, Fife, on May 18.
It’s an eliminator for a British light-heavyweight title and John, who divides his time between Galashiels and Melrose, is taking on London fighter Duane Sinclair.
The winner could then face either Joshua Buatsi or Frank Buglioni.
John has had a nine-year career in boxing and won 11 of his 12 professional fights – including British title challenges – before a shoulder injury and problems with cuts around the eyes, caused by head clashes and the eyes swelling and closing, halted his progress.
His motivation for the sport dwindled during his 19 months or so away from the ring – but now he is keen to be involved again.
“My manager, Steve Goodwin, from London, has got me back in action in Glenrothes and put me back into the British title mix,” he said.
Dublin-born John, who has a degree in finance, fought previously at super middleweight, so has stepped up a division to light-heavyweight.
He won a string of Scottish and British titles as an amateur and competed for Scotland and Ireland at international tournaments all over the world.
A couple of belts have come his way as a full-time fighter, with victories over Dalton Miller and, in a fight shown live on Channel 5 – in which he injured his shoulder and elbow – Hungarian champion Norbert Szekeres.
John, who has a daughter, Scarlett (5), said: “I am itching to get back and, with Scottish boxing being on a high at the minute, I have always seen myself at the top of the game. I have the motivation back.”
John’s opponent at the Gilvenbank Hotel in Glenrothes, Duane Sinclair, is six feet four, unbeaten in eight fights and, according to John: “Really tall and awkward”.
But John, who has sponsorship from Galashiels firm K&S Walker Electricals, is nevertheless confident, saying: “I just feel I am the better boxer. I feel my boxing skills will take care of it.”
Fife trainer Stevie McGuire had been another great influence and John added: “Having him in my corner is like a 12th man on the football park.”