After two seasons with Toronto, he returned to San Jose in 2019,[1] and was traded to the Pittsburgh Penguins before the 2020 Stanley Cup playoffs.

Marleau, one of the most important players of the Sharks for nearly 20 seasons, was known as one of the fastest skaters in the NHL and exhibited a high standard of playing ability combined with gentlemanly conduct.

This earned him two nominations for the Lady Byng Memorial Trophy and made him a popular player both among fans and his professional peers.

In his rookie campaign in 1995–96, Marleau exploded onto the scene in Seattle scoring 32 goals and 74 points, leading his team to a playoff loss to the defending Memorial Cup champions, the Kamloops Blazers, featuring future NHL star Jarome Iginla.

In the playoffs, Marleau led the Thunderbirds to the club's first Western Conference Championship before the team bowed out in the WHL Finals to the eventual Memorial Cup runner-up Lethbridge Hurricanes in four games.

Marleau finished second in the WHL's Player of the Year voting, losing to Peter Schaefer of the Brandon Wheat Kings.

Although he struggled early in his career, Marleau learned to combine his excellent offensive talents with defensive prowess from former Sharks head coach Darryl Sutter.

New rule changes implemented by the NHL at the start of the first season back from the lockout that emphasized speed may have contributed to Marleau's successful campaign.

The Sharks were quickly considered a contender once acquiring "Jumbo Joe", but were upset by the eighth-seeded Edmonton Oilers in the second round.

At the end of the season, Marleau was voted one of three finalists for the Lady Byng Memorial Trophy, awarded to the NHL's most gentlemanly player, but lost out to Pavel Datsyuk of the Detroit Red Wings.

In the off-season, Marleau signed a two-year, $12.6 million contract extension in August 2007 to keep him with the Sharks until the end of the 2009–10 season.

Despite his efforts, which included eight points in 13 games total for the playoffs, the Sharks were eliminated in the second round for the third consecutive year.

In the midst of a rejuvenated year for Marleau, overcoming his previous season's dismal offensive output, he was selected to the 2009 NHL All-Star Game in Montreal, replacing the injured Pavel Datsyuk.

Later in the year, while Blake was injured, Marleau was promoted to alternate captain, joining Joe Thornton and Dan Boyle.

[27][28] Entering the open market for the first time in his career, Marleau was heavily courted by multiple teams, including the San Jose Sharks, Toronto Maple Leafs, Anaheim Ducks and Dallas Stars.

[31] Marleau cited returning to Canada, as well as the young Maple Leafs projection as a Stanley Cup contender as reasons for signing in Toronto.

[32] Additionally, he cited the Maple Leafs' advanced sports science department as benefit of signing with the team (during free agency, Marleau was in the midst of one of the longest iron man streaks in NHL history).

[37] Later during the season, he passed Maple Leafs' great Darryl Sittler with 1,122 career points, becoming 58th on all-time list.

[38] On November 26, 2018, Marleau played in his 1,600th NHL game and became the 11th player to reach the mark, while also making an assist in the Maple Leafs' 4–2 win over the Boston Bruins.

[45] Marleau received a standing ovation during his first home game on October 13; he recorded an assist in a 3–1 win over the Calgary Flames.

[50] His Cup ambitions would quickly end however as the Penguins were defeated in four games by the Montreal Canadiens, who were the lowest-seeded team to make the postseason.

In the summer following his silver-medal effort with Canada, he was invited to the national team's development camp for the 2006 Winter Olympics, but was omitted from the final roster.

On December 30, 2009, Marleau was selected to play for Canada at the 2010 Winter Olympics in Vancouver, where he won a gold medal.