Hamonic's contract extends through the 2024-25 season.
"Travis is a key component of our group," Senators general manager Pierre Dorion said in a team release. "He routinely sets a good example for our younger players with work ethic and accountability, his fearlessness and with a determination level that he seems to exceed each time he steps on the ice. He's a leader with strong character and someone we're very pleased to see returning."
Hamonic, 32, recorded 21 points (six goals, 15 assists) in 75 games last season with Ottawa.
He has totaled 229 points (50 goals, 179 assists) in 793 career games with the New York Islanders, Calgary Flames, Vancouver Canucks and Senators. He was selected by the Islanders in the second round of the 2008 NHL draft.