He moved to the United Kingdom as a 19 year-old and was based with fellow New Zealand team member Mark Todd, and in 2017 with Andrew Nicholson.

[5] Campbell was a reserve for the New Zealand's eventing team at the 2018 World Equestrian Games in Tryon, North Carolina with his Dutch Gelding Cleveland.

[2][7] After finishing in 22nd place overall at the Tokyo Olympics, a diagnosis of stomach ulcers in the horse led to a stepping back from competition.

[9] He and his wife, fellow eventer Georgie Campbell, were married in December 2020, and lived in Marlborough, running stables in Ramsbury, Wiltshire.

[2][3] In May 2024, Georgie Campbell was killed in a riding fall while competing in the Bicton International Horse Trials in Devon, England.