He played four seasons of junior with the Lethbridge Hurricanes before joining the Blackhawks in 2005–06, becoming a key component in their success including three Stanley Cup championships.

[2] He also played spring hockey with the Pacific Vipers, along with three future Chicago Blackhawks teammates, Colin Fraser, Troy Brouwer and Andrew Ladd.

He scored 11 points in 17 post-season games as the Blackhawks made it to the Western Conference Finals, where they were defeated by the defending Stanley Cup champion Detroit Red Wings.

Seabrook recorded three goals and 36 assists for 39 points in 79 games in the 2016–17 season as the Blackhawks as a team finished the season as the top seed in the Western Conference before being held pointless in the Blackhawks first round exit in the opening round of the 2017 playoffs in a four game sweep at the hands of the eighth seeded Nashville Predators.

[16] On December 11, 2018, Seabrook and teammate Duncan Keith became the first pair of defencemen, and the seventh duo in NHL history to play 1,000 games together.

[17][18][19] On December 26, 2019, the Blackhawks placed Seabrook on long-term injured reserve after announcing he would require three separate surgical operations to repair his right shoulder and both hips.

[21] Seabrook intended to rejoin the Blackhawks prior to the 2020–21 season, but injured his back days before team's pre-season training camp.

[23] On July 27, 2021, the Blackhawks traded Seabrook's contract to the Tampa Bay Lightning in exchange for Tyler Johnson and a second-round draft pick in 2023.

Returning the following year in 2005 in the United States, he matched his three-point total from the previous tournament and helped defeat Russia 6–1 in the final to capture Canada's first gold medal that began a five-year run.

On December 30, 2009, Seabrook was called and asked to play for Canada at the 2010 Winter Olympics in Vancouver, along with Blackhawks teammates Duncan Keith and Jonathan Toews.

[29][30] On February 25, 2014, Seabrook, along with Blackhawks teammate Duncan Keith, made a cameo appearance in the episode "Virgin Skin" on the NBC drama Chicago Fire.