The deal, inked just minutes after the official opening of free agency, carries a $6.5-million cap hit.
The 34-year-old centre from Hearst, Ont., has strong ties to Ottawa -- he played Junior 'A' (Cumberland Grads) and Major Junior (Gatineau Olympiques) in the capital area from 2004 to 2008 -- and was considered a top target for the Senators leading up to signing season.
He now joins a young club emerging from an extensive rebuild and looking poised to end what has been a five-year playoff drought. The Senators have been one of the busiest teams this off-season so far, acquiring forward Alex DeBrincat from the Chicago Blackhawks last week before trading for starting goalie Cam Talbot and sending Matt Murray to Toronto in a cap-clearing move.
Giroux spent the first 15 years of his NHL career with the Philadelphia Flyers, serving as the franchise's captain for a decade before being traded to the Florida Panthers at this past season's trade deadline. He registered 65 points in 75 games between the two teams in 2021-22.
Giroux has 923 points in 1,018 career regular-season NHL games, with a further 81 points in 95 playoff games.