Amateur

Armstrong was born in Lloydminster, Saskatchewan, but grew up in Saskatoon, Saskatchewan. He attended Sacred Heart High School in Yorkton, Saskatchewan for grade 11 and 12 while playing AAA Midget, and also St. Joseph High School in Saskatoon with his brother Colby Armstrong, who also played in the NHL.

After playing minor hockey with the Saskatoon Redwings (and figure skating out of Martensville and Saskatoon Figure Skating Club, coached by his mother Rosemary), Armstrong left to play Midget AAA with the Yorkton Mallers, where he scored 44 goals and 77 points in 40 games, finishing 3rd in league scoring. Armstrong began playing for the Kootenay Ice of the Western Hockey League (WHL) in the 2002–03 season, scoring 6 goals. He was then traded to the Everett Silvertips during the 2003–04 season, scoring 18 goals.

Professional

On September 15, 2004, he was signed as a free agent by the San Jose Sharks. Armstrong was immediately sent down to the Cleveland Barons for two seasons, scoring a combined 12 goals. Armstrong spent the next three years with new Sharks affiliate, the Worcester Sharks before he made his NHL debut in the 2008-09 season with San Jose on November 29, 2008, in a 3–2 win over the Phoenix Coyotes playing on a line with Jeremy Roenick and Jody Shelley.^[1]

On July 2, 2009, Armstrong signed with the Calgary Flames.^[2] He was then assigned to its affiliate, the Abbotsford Heat. On March 3, 2010, Armstrong was traded to the Detroit Red Wings, linking up with their affiliate, the Grand Rapids Griffins.^[3] He joined the Utah Grizzlies in November 2010, playing in two games and recording two assists and four penalty minutes. He was signed by Barys Astana on November 21, 2010. In late 2010 on December 29, Armstrong was signed on to play with Augsburger Panther of the Deutsche Eishockey Liga for the remainder of the season.^[4]

Armstrong was signed to a contract by the Elmira Jackals on October 8, 2011.^[5] After seven games with the team, Armstrong was signed to a PTO contract by the Binghamton Senators on November 17, 2011.^[6] He was later released back to Elmira on December 17.^[7] Armstrong signed with Finnish team SaiPa on December 25, 2011, and finished the season with the team.

Without a contract extension offer from SaiPa, Armstrong had an unsuccessful try-out with HC Ambrì-Piotta of the Swiss NLA before returning to the Utah Grizzlies of the ECHL for the commencement of the 2012–13 season where he was captain of the Grizzlies.

On July 19, 2013, Armstrong signed as a free agent to return to Europe on a one-year contract with German club, EV Landshut of the DEL2.^[8]

Following another season in Europe in Sweden and Germany with HC Vita Hästen and Heilbronner Falken respectively, Armstrong returned as a free agent for a third stint with the Utah Grizzlies, signing a one-year contract on August 4, 2015.^[9] Prior to the 2015–16 season, Armstrong was placed on waivers by the Grizzlies and was claimed by the Reading Royals on October 11, 2015.^[10]