After a courtship lasting almost a year and a half, the Old School BC light welter has agreed terms with the Oscar De La Hoya-led company.
McKenna will be managed in the pros by Sheer Sports, with a backroom set-up mirroring that of Donegal middleweight Jason Quigley.
Over the past year he has spent periods out in the U.S. sparring fighters such as WBO super bantamweight champion Jessie Magdaleno.
The Ulster boxer had looked set to go pro while he was still 16 last year, with a debut in Mexico mooted, but he would delay the move.
He subsequently finished runner up in the 2016 Under 18s before winning gold in the extremely prestigious Nikolay Pavlyukov Memorial in Russia this year. McKenna did not enter the Irish Under 18s afterwards and was instead due to head to the Commonwealth Youth Games in July, but would withdraw to focus on his studies.
McKenna is younger brother to 2016 Senior light flyweight champ and 2017 bantamweight runner-up Stevie, while eldest sibling Gary is also an accomplished fighter, representing Ireland at the 2014 EUs and 2016 World Universities.
During an impressive underage career McKenna claimed eight Irish titles, European Schoolboys gold, and European Junior silver.
McKenna passes out 19 year old Kilnamanagh lightweight Liam Gaynor as Ireland’s youngest professional boxer.
A debut date for McKenna, who will be based in Los Angeles initially, will be set shortly.