Matthias finished last season with a career-best 14 goals last season and 21 points.
"I am happy to get it out of the way," Matthias said. "The last contract I did was two days before [training] camp. Now I can just focus on training and getting ready for the season."
The two-way center moved up the Panthers depth chart with an explosive March, when he scored 11 goals and two assists in 16 games.
"Shawn is a hardworking player who played well for our club last season," Florida GM Dale Tallon said. "He took steps in his development last year, scoring a career high in goals. We look forward to him improving and playing an important role on our club."
TSN reported the center will earn $1.75 million per year.
With long-time Panther Stephen Weiss signing with the Detroit Red Wings earlier in the day, Matthias said he hopes to take on a more prominent leadership role with the team this coming season.
"I want to be the guy now," Matthias said. "I want to take on that bigger role now."
Acquired in a 2007 trade with the Red Wings, Matthias has 39 goals and 42 assists for 81 points in 253 career games, all with Florida.
The Panthers also announced the singings of defenseman Mike Mottau and center Jesse Winchester to a one-year, two-way deals and winger Joey Crabb to a two-year deal.
Florida also acquired winger Philippe Lefebvre from the Montreal Canadiens in exchange for George Parros and a seventh-round pick in 2014.