Brassard, who will turn 29 on Sept. 22, leaves the Rangers after parts of four seasons that included a trip to the 2014 Stanley Cup Final. Last season, he scored a team-high 27 goals for the Rangers, who were eliminated in the Eastern Conference First Round by the Pittsburgh Penguins in five games.
Brassard said he is excited to play for the Senators, something he has thought about ever since Ottawa reached the 2007 Stanley Cup Final against the Anaheim Ducks.
"A long time ago when I was younger, when the Sens made the push to the Stanley Cup Final, [my agent] brought me to one of those games," Brassard said. "I just fell in love with the atmosphere there, the rink. From that moment, I was like, 'Maybe one day I'll play here.'"
Selected in the first round (No. 6) by the Columbus Blue Jackets in the 2006 NHL Draft, Brassard played parts of five seasons in Columbus before being traded to New York in 2012-13. He said he is very familiar with many Senators players.
"I know a lot of guys. I was skating with them in the summers," Brassard said. "I got to know [defenseman] Cody Ceci and [forward] Mark Stone at the World Championship this summer. I got along with those two guys really well. I know [forward] Mike Hoffman from junior, I know [Jean-Gabriel] Pageau from living in Hull and kind of grew up in the same city as him.
"I really like the balance of their team. I think they have a really good mix there. They have a lot of young guys coming up. But I do think this team is mature now and we have to win next season."