One of the most respected and successful tennis coaches in Division II history, Earnshaw played men's tennis for four seasons (1991-92 to 1994-95) at Georgia College & State University and helped the Bobcats to top 10 national rankings each year. He earned his bachelors in chemistry in 1996 and master's in physical education from GCSU
in 1998.

After GCSU, he became head tennis coach at Armstrong State University for 15 years where he guided both teams to a 747-118 record, including a 411-35 mark for women. His programs reached 12 NCAA Division II finals, 16 Final Fours, 21 NCAA quarterfinals, produced 35 ITA All-Americans, 30 ITA Scholar-Athletes, and 15 ITA All-Academic teams. His women's programs captured six of the nine NCAA Division II crowns between 2005-13, while his men's team won three times during that stretch. Additionally, his squads swept both the men's and women's team titles on three occasions - 2008, 2009 and 2012.

He was named the Peach Belt men's tennis Coach of the Year six times and the women's Coach of the Year 12 times.  He was named the ITA National Women's Coach of the Year four times.

Currently, he's the head women's tennis coach at North Carolina State (since 2014) and has a 150-76 record. He led the Wolfpack to the semifinals of the 2021 NCAA Division I Tournament. The 2019 ACC Women's Tennis Coach of the Year, Earnshaw has led NC State to six straight NCAA Championships bids, the longest streak in school history. NC State won a record 26 matches, reached the ITA National Team Indoor Championship semifinals, and advanced to the quarterfinals of NCAA Tournament in 2022.

For his career, he has a 897-194 record (.822 winning percentage).