Marleau was selected by the San Jose Sharks as the second overall pick in the 1997 NHL Entry Draft, showcasing his potential as a young talent. He made his NHL debut during the 1997–1998 season and quickly became a key player for the Sharks. Marleau spent the majority of his career with the San Jose Sharks, where he became the franchise leader in numerous statistical categories, including games played, goals, and points. He consistently displayed his scoring ability, recording multiple 30-goal seasons and eclipsing the 1,000-point milestone during his tenure with the Sharks. One of Marleau's most remarkable achievements is his consecutive games played streak, which reached a record-breaking 899 games, demonstrating his durability and dedication to the sport.