Jermaine Ainsley returned to his home region at the start of 2021 after playing in Australia since 2015. The explosive front-rower came with a wealth of experience after earning 60 Super Rugby caps from Australian Super Rugby teams between 2016-20 and the Otago Boys High School ex-pupil played for the Wallabies three times in 2018.

Ainsley has quickly solidified himself as a starting prop and has earned 27 caps for the Highlanders, bringing his Super Rugby total to an impressive 87 caps. He was rewarded in 2022 for consistent performance with selection to the Māori All Blacks for their two test series against Ireland and then in 2023 he was selected for the All Blacks XV squad to play two test series in Japan. He was also awarded Highlanders Forward of the Year at the annual Highlander's Awards in 2023 for the second year in a row.

His father, Joe Mcdonnell, also played for the Highlanders when the club was founded back in 1996.