A right handed opening batsman, Spearman made his international debut for New Zealand in a Test Match in December 1995 against Pakistan at Christchurch. He was never able to secure his spot in the side and only scored one Test hundred, an innings of 112 against Zimbabwe.
After giving up on his international career, he moved to England in 2001 to pursue a career in banking. However after meeting with fellow New Zealander, John Bracewell, he was asked to play for the team he was coaching, Gloucestershire County Cricket Club. Spearman immediately became a favourite in Bristol, when he hit a century in his first match.
In 2004 he hit 341 against Middlesex at Gloucester. His innings contained 40 fours and six sixes and was the highest ever score by a Gloucestershire batsman, beating the record of WG Grace. Since then he has continued to score runs and has gone on to add two more double centuries.
In 2006 he became just the 4th player from his county to score a century in both innings against Northamptonshire. He finished the year with 1370 runs in the Championship.
He attended Kelston Boys' High School.