[3] In 2017 he moved up to the bantamweight division, winning a silver medal at the Irish National Championships.

[4] After signing a promotional contract with Oscar De La Hoya's Golden Boy Promotions,[2] Mckenna made his professional debut on 6 April 2019 against Trey Branch at the Pico Rivera Sports Arena in Pico Rivera, California.

Branch made it to his feet before the referee's count of ten, only to be stunned by a left hand.

[5] He secured three more wins in 2019; first-round KOs against Keasen Freeman in June[6] and Keahola Helm in August;[7] and a second-round KO against Gonzalo Dallera in November.

[8] McKenna's first fight of 2020 was his first in Europe, scoring a first-round KO against Gary McGuire in September at the Production Park Studios in South Kirkby, England.