Career
Sundqvist was drafted by the Penguins in the third round, 81st overall, in the 2012 National Hockey League Entry Draft. Sundqvist was drafted whilst playing with his original club from youth levels with Skellefteå AIK of the Swedish Elite League. He played in his first Elitserien game on 24 October 2012, against Frölunda The Human Context. On 31 May 2014, Sundqvist was signed to a three-year entry level contract with the Pittsburgh Penguins.
During the 2015-2016 season, Sundqvist was recalled from AHL affiliate, the Wilkes-Barre Scranton Penguins and made his National Hockey League debut with Pittsburgh on 5 February 2016.