For a couple of years McKean fought in both MMA and Muay Thai with only one defeat in all combat sports.
[4] McKean made his professional boxing debut on 31 October 2014 against Luke Barclay on the Alex Leapai vs Malik Scott undercard at Logan Metro Sports Centre, Crestmead, Queensland, Australia.
[7] McKean stopped James Cook in the 3rd round in the quarter-finals, won by unanimous decision against Elijah Tevaga Sa'lesui in the semi-finals and won by unanimous decision against UFC Fighter Tai Tuivasa in the finals to win the $15,000 and the Frank Bianco Cup.
[8] In March 2017, McKean fought in a rematch against Hunter Sam for the Interim Australian national heavyweight title.
During the fight Hunter Sam was deducted a point in the first and seventh round for illegal low blows landed against McKean.
[9] In July 2017, McKean called out the full Australian National Champion Will Nasio which was televised on TV.
[13] Due to the injury, McKean had to turn down a lot of major international boxing fights including some in Canada for the Commonwealth title.
[14] McKean finished his 2018 with a fight against Nigerian born Australian and former IBF Pan Pacific champion Roger Izonritei.
[25] Throughout the end of 2019, negotiations were happening to have Demsey McKean fight former WBA World Heavyweight Champion Lucas Browne.
Lucas Browne agreed with McKean promoter Angelo Di Carlo for a March 2020 fight.
[23] Jonathan Rice spoke a lot of trash talk in their upcoming fight, but McKean didn't care for it.
[30] In October 2020, McKean expressed his interest in fighting Efe Ajagba, a boxer who fought and defeated Jonathan Rice as well.
[32] McKean was scheduled to fight again in December 2020 defending his regional titles against Bowie Tupou on the Tim Tszyu vs Bowyn Morgan undercard.
[34] In May 2021, McKean made his in ring return against unbeaten New Zealand born Samoan boxer Kiki Toa Leutele.
[41] McKean was stopped by Moses Itauma in the first round on 21 December 2024, at Kingdom Arena in Riyadh, Saudi Arabia in a fight which was part of the undercard for the heavyweight world title rematch between Oleksandr Usyk and Tyson Fury.