[3] Whitney enrolled at Thayer Academy, a college-prep school in Braintree, Massachusetts, in 1998, and logged significant playing time with their hockey team.

Head Coach Jack Foley often paired Whitney, a freshman, with senior Brooks Orpik, his future rival in college (being on separate ends of the Boston College-Boston University Rivalry), and later his teammate on the Pittsburgh Penguins.

[citation needed] After graduating from high school, Whitney accepted a full scholarship to play for Boston University under Jack Parker.

Under the guidance of new general manager Ray Shero, the Penguins improved from a last-place finish in the Eastern Conference the year before, to a playoff berth, with Whitney part of the youth movement in Pittsburgh that included forwards Sidney Crosby, Evgeni Malkin, Jordan Staal and goaltender Marc-André Fleury.

[6] During the 2007 off-season, Whitney signed a six-year, $24 million contract with a no-trade clause, avoiding his pending restricted free agency.

However, the Penguins finished second in the Eastern Conference and Whitney contributed six points in the 2008 Stanley Cup Playoffs, as Pittsburgh made it to the Finals against the Detroit Red Wings.

After an attempt using orthopedic inserts in his skates failed, Whitney underwent osteotomy, a surgical procedure to realign the bones in his left foot, on August 15, 2008.

After playing one game with Wilkes-Barre/Scranton, as part of a conditioning stint, Whitney made his return to Pittsburgh, in a 2–0 loss to the Tampa Bay Lightning, on December 23, 2008.

[10] He scored one goal and five assists during the 2009 Stanley Cup playoffs, as the Ducks made it to Game 7 of the Western Conference Semi-Finals, losing to the Detroit Red Wings.

[11] On March 3, 2010, Whitney was traded along with a 2010 sixth round draft pick (Brandon Davidson) to the Edmonton Oilers in exchange for defenseman Ľubomír Višňovský.

[21] As a free agent, Whitney left Russia after one season and signed a one-year contract with Swedish club Modo Hockey of the SHL on June 24, 2015.

Whitney posted better numbers than the year previous, picking up five points (one goal and four assists) in seven games, as the United States finished in fourth place.

With injuries to fellow defensemen Paul Martin and Mike Komisarek, Whitney was selected as a replacement to represent the United States in the 2010 Winter Olympic Games, held in Vancouver, British Columbia.

During this time, Whitney also wrote a blog and hosted a podcast on Barstool Sports throughout the games, sharing his thoughts, feelings and experiences.

[26] In June 2022, Whitney went viral on social media for posting a video on Twitter about his frustrations during his time at Toronto Pearson International Airport.