He broke the course record at Pannal Golf Club, Harrogate, England on 24 August 2005, shooting 63, 9-under-par at age 16.

He reached the semi-finals of The Amateur Championship in 2010, losing to the eventual winner Jin Jeong of South Korea.

Nixon entered the qualifying school for the European Tour in autumn of 2010, and came through all three stages to earn his playing rights for 2011, prompting him to turn professional.

After a promising start to the season, he failed to make a cut between July and November but returned to Qualifying School at the end of the year to regain his card.

In 2018, Nixon had a strong year, finishing 13th at the Commercial Bank Qatar Masters, tied for 18th at the BMW International Open, ninth at the Porsche European Open and eighth at the Andalucía Valderrama Masters.