[3][4][5] As a freshman with the Metro State Roadrunners in 2005–06, Wagstaff started seven games and played in all 31 contests as he averaged 5.2 points and 3.3 rebounds.

[2][6][7] As a sophomore in 2006–07, Wagstaff was named honorable mention All-RMAC East Division after averaging 11.7 points and a team-leading 6.7 rebounds per game.

[2][6][8] As a junior in 2007–08, Wagstaff was named first-team All-RMAC East Division and led the team in scoring and rebounding, while starting all 31 games.

[11] After the team folded in May 2009,[11] he had a one-game stint with the Canberra Gunners in the South East Australian Basketball League[12] before signing a two-year deal with the Perth Wildcats in June 2009.

[15] He helped the Wildcats win the 2010 championship with a 2–1 grand final series victory over the Wollongong Hawks.

[16] During the NBL off-season, Wagstaff played for the Perth Redbacks of the State Basketball League (SBL).

[21][22] For the 2011–12 season, Wagstaff was named the NBL Best Sixth Man after averaging a career-high 11.5 points per game off the bench.

[23] He helped the Wildcats reach the NBL Grand Final series, where they lost 2–1 to the New Zealand Breakers.

Wagstaff helped the Wildcats return to the NBL Grand Final in the 2012–13 season, where they again faced the New Zealand Breakers and lost 2–0.

[25] On 24 October 2014, Wagstaff was involved in an ugly on-court incident with Sydney Kings forward Josh Childress.

The vision of the incident was seen around the world, as Childress was handed a one-game suspension and a fine for unduly rough play and bringing the game into disrepute.

In the grand final series, the Wildcats defeated the New Zealand Breakers 2–1 to win the NBL championship.

On 19 April 2016, Wagstaff signed a two-year contract extension with the Wildcats, keeping him at the club until at least the end of the 2018–19 season.

[34] The Wildcats finished the regular season in third place with a 15–13 record and played the Cairns Taipans in the semi-finals.

He went on to help the Wildcats to a 3–0 grand final series sweep of the Illawarra Hawks, as he claimed his fourth NBL championship.

On 1 December 2017, Wagstaff scored 19 points in 23 minutes off the bench in an 89–73 victory over the Breakers, helping the Wildcats win in New Zealand for the first time since 2013.

[41][42] The Wildcats finished the regular season in third place with a 16–12 record before losing in straight sets to the 36ers in the semi-finals.

In March 2019, he won his fifth NBL championship after the Wildcats defeated Melbourne United 3–1 in the grand final series.

Wagstaff and long-time teammate Damian Martin became the first players in NBL history to win five championships with just one club.

[57] During the grand final series, he passed Anthony Stewart (419) for second place on the Wildcats' all-time 3-pointers list.

[81][82] He broke Grace's record two days later, playing his 483rd game in a loss to the South East Melbourne Phoenix.

[90] He received a call-up to join the Australian Boomers in June 2010 ahead of their three-game series with Argentina.

[93] Wagstaff's next international duties came when he was named in a 20-man Boomers squad ahead of the 2017 FIBA Asia Cup.