He spent most of his career in the National Hockey League (NHL) with the Montreal Canadiens, Tampa Bay Lightning and Ottawa Senators.

Towards the end of an 81-point campaign for Pyatt in his fourth and final major junior season in 2006–07, the Rangers signed him to a three-year, entry-level contract on March 12, 2007.

On June 30, 2009, Pyatt was traded from the New York Rangers, along with Scott Gomez and Michael Busto, to the Montreal Canadiens for Chris Higgins, Ryan McDonagh, Pavel Valentenko and Doug Janik.

On August 4, 2014, he agreed to a one-year contract with an optional second season with Genève-Servette HC of the National League (NL), to play alongside his brother, Taylor.

[9] After clearing waivers, he was assigned to the AHL, however before he could report he was traded by the Senators, along with Mike McKenna and a 2019 sixth round pick, to the Vancouver Canucks in exchange for Anders Nilsson and Darren Archibald on January 2, 2019.

[11] Un-signed by the Sharks, Pyatt returned to Europe as a free agent in securing a one-year contract with Swedish club, Skellefteå AIK of the SHL, on July 26, 2019.

[12] On February 6, 2020, Pyatt parted ways with Skelleftea AIK to join the SC Rapperswil-Jona Lakers in the National League (NL) for the remainder of the season.

During his third OHL season with the Saginaw Spirit, Pyatt was chosen to represent Team Canada at the 2006 World Junior Championships in Vancouver, helping them to a gold medal as the tournament host country.