A Stanley Cup winner known for his versatility, physical play, energy, defense and solid faceoff work, Richardson played four seasons in the Ontario Hockey League with Owen Sound before turning pro.

Richardson scored 27 goals for Owen Sound in 2002-03 and was selected by the Avalanche that year in the fifth round (No. 163) of the NHL Draft. He had his best junior season in 2004-05, when he had 41 goals and 97 points, finishing third in the league in each category. He was runner-up for the league's Most Outstanding Player award.

Richardson made his NHL debut Nov. 27, 2005 with Colorado against the Vancouver Canucks. His first NHL point came on an assist Jan. 9, 2006, against the St. Louis Blues and he scored his first NHL goal Jan. 28, 2006, against the Canucks. Richardson made his Stanley Cup Playoff debut that spring and scored his first playoff goal April 28, 2006, against the Dallas Stars.

In 2006-07 Richardson led Colorado with three shorthanded goals, becoming the first Avalanche player to score three shorthanded goals in a single season since Joe Sakic in 2000-01.

Richardson split the 2007-08 season between the Avalanche and Lake Erie of the American Hockey League. On June 21, 2008, he was traded by Colorado to the Los Angeles Kings for a 2008 second-round draft pick. Richardson got his first NHL hat trick Oct. 23, 2010, against the Avalanche.

In 2011-12 he appeared in 13 playoff games, scoring a goal and getting an assist, while helping the Kings win the Stanley Cup. On July 5, 2013, he signed a two-year, free agent contract with Vancouver.

Richardson played 73 games for the Canucks in 2013-14, scoring 11 goals (including a team-high two shorthanded) and 23 points. Though injuries limited him to 45 games for the Canucks in 2014-15, he had five multipoint games.

Richardson signed as a free agent with the Arizona Coyotes on July 1, 2015. He got his 100th NHL assist Jan. 4, 2016, against Vancouver.