Pearson played major junior hockey with the Barrie Colts in the Ontario Hockey League. On August 3, 2012, Pearson signed a three-year entry-level contract with the Los Angeles Kings, who had drafted him with the last pick of the first round in the 2012 NHL Entry Draft. In 2013, the Kings recalled Pearson after completion of his first professional season with affiliate, the Manchester Monarchs of the American Hockey League, to be one of their "black aces" on their taxi squad during the Stanley Cup playoffs. On May 18, 2013, he played right wing on the Kings fourth line in his first NHL game in a playoff game against the San Jose Sharks. On December 3, 2013, Pearson was sent back down to Manchester. On June 13, 2014 Pearson helped lead the Kings to a Stanley Cup victory over the New York Rangers. In the 2014–15 season, Pearson played a majority of the season with Jeff Carter and Tyler Toffoli, with the line being dubbed "That 70s Line" since all three had numbers in the 70s. Pearson was injured on January 10, 2015, suffering a broken left leg during a game against the Winnipeg Jets. The injury would cause Pearson to miss the remainder of the 2014–15 season. On April 2, 2015, Pearson signed a two-year contract extension worth $2.8 million. In October 2016, Pearson was suspended for four games for an illegal hit to the head of Brandon Davidson. As an impending restricted free agent following the 2016–17 season, having established career bests with 24 goals and 44 points, Pearson agreed to a four-year contract extension worth $15 million on May 8, 2017. Pearson through the first year of his new contract in 2017–18 season, was one of four Kings skaters to appear in all 82 games, he ranked sixth in scoring with 15 goals and 40 points. With the Kings off to slow start to start the 2018–19 season, Pearson mirrored the Kings struggles by registering just 1 assist through 17 games.
Pearson grew up in Kitchener, Ontario, with his sister Ali and parents Kim and Tim Pearson. His father and sister were both involved in hockey; his father worked for equipment company Bauer Hockey and his sister worked for the Kitchener Rangers. Pearson married his longtime girlfriend Meaghan Loveday in the summer of 2018.
