As a youth, Gionta played in the 1993 Quebec International Pee-Wee Hockey Tournament with a minor ice hockey team from Rochester, New York.

Gionta is the middle child of Sam and Penny Gionta. He and his wife, Harvest, have three children. Gionta has a brother, Stephen, who played for the New Jersey Devils and New York Islanders. He also has an older brother Joe, who also played for the Aquinas Institute Hockey Team and graduated in 1994. Brian Gionta has a home in the Rochester, New York area where his parents still reside.

Gionta was drafted 82nd overall by the New Jersey Devils in the 1998 NHL Entry Draft. The diminutive but fiery forward attended high school at the Aquinas Institute in Rochester, New York, where in 1993–94 he was selected as their Rookie of the Year. He then skated for Boston College from 1997 to 2001, winning a national championship as Eagles captain in the 2000–01 season. He was mentored by former NHL forward Marty Reasoner, also a Rochester native, and enjoyed his best statistical season in his freshman year on a line with Reasoner, posting 30 goals and 62 points in 40 games as the Eagles fell to the University of Michigan in the national championship game in Boston.

Gionta, who joined the New Jersey Devils during the 2001–02 season, was a member of the 2003 Stanley Cup Finals-winning team that prevailed over the Mighty Ducks of Anaheim. During the 2004–05 NHL lockout, he played for the Devils’ American Hockey League (AHL) affiliate, the Albany River Rats. In 2006, he was a member of the 2006 United States’ men’s team that competed in Turin, Italy.

Largely serving on the right wing of the Devils’ prolific “EGG” line – which included Patrik Eliáš and Scott Gomez – Gionta was one of the Devils’ most effective offensive players during his tenure in New Jersey. On March 28, 2006, Gionta became the first Devils player to score 40 goals in a season since Eliáš and Alexander Mogilny each reached the mark in the 2000–01 season.

In the last game of the 2005–06 season, Gionta broke Pat Verbeek’s franchise record for goals in a season, finishing with 48. In that season, he also finished with his highest point total to date, with 89 in all 82 games of the regular season. On October 27, 2007, Gionta scored the first Devils’ goal in the history of the Prudential Center in the second period of a 4–1 loss to Ottawa. (Chris Neil scored the first ever).

On July 1, 2009, Gionta signed a five-year contract for $25 million with the Montreal Canadiens. It reunited him with former Devils teammate Scott Gomez.

^ 1: Michael Cammalleri had previously scored the 20,000th goal in Canadiens’ franchise history in 2009. Cammalleri’s mark included the Canadiens time in the National Hockey Association.

Just prior to his second season with the club, in 2010–11, on September 29, 2010, Gionta became only the second American-born player to serve as team captain of the Canadiens, after Chris Chelios.

During the 2012–13 season, Gionta played in all 48 games of the lockout-shortened season and registered 14 goals and 12 assists while leading the Canadiens on a remarkable comeback from last in the Eastern Conference to their 23rd Northeast Division title. On March 5, 2013, Gionta scored the 20,000th NHL goal in the history of the Canadiens in a game against the New York Rangers. Entering the 2013 Stanley Cup playoffs as the second seed against the Ottawa Senators, Gionta tore his bicep in Game 1 and was forced to undergo season-ending surgery to repair it.

On July 1, 2014, Gionta signed a three-year free-agent deal with hometown team, the Buffalo Sabres, for $4.25 million per year. On October 7, 2014, Gionta was named captain of the Sabres. Gionta played in his 1,000th NHL game on March 27, 2017 against the Florida Panthers in Buffalo.

The Sabres opted not to re-sign Gionta in the 2017 offseason after reacquiring Jason Pominville in a trade. The Sabres’ owned-and-operated American Hockey League club, the Rochester Americans, signed Gionta to their practice squad on October 9, 2017. Since the practice-only contract is not with the NHL, Gionta was able to participate in the Winter Olympics, following the NHL’s announcement not to accommodate an Olympic break due to financial disputes with the IOC. Gionta was officially named to Team USA’s pre-Olympic roster on October 18, 2017. Gionta has since been named USA team captain. Gionta admitted turning down NHL offers to participate in the Olympics and intends to re-sign with the league after the Olympics end.

On February 25, 2018, Gionta signed a one-year, $700,000 contract for the remainder of the season with the Boston Bruins.

Gionta announced his retirement on September 24, 2018, and revealed that he had joined the Sabres as a development coach.

On January 29, 2018, the Americans upgraded Gionta’s practice-squad contract to a one-game professional tryout contract, allowing him to play the Americans February 2, 2018 game against the Toronto Marlies before leaving for the Olympics. Gionta scored a goal in the game but the Americans lost 4-2.