The 39-year-old Timonen will return for his eighth season with the Flyers. He was acquired in 2007 from the Nashville Predators along with Scott Hartnell in exchange for Nashville's first-round pick in the 2007 Entry Draft.
In seven seasons with the Flyers, Timonen has won five Barry Ashbee trophies as the team's best defenceman, including the last three. He ranked second in team history behind Eric Desjardins, who won the award seven times.
He has also made two of his five Olympic appearances with Finland during his time as a Flyer, winning bronze in both 2010 and 2014. He was recognized for his 1,000th career NHL game in March 2013.
Timonen had six goals and 32 points in 77 games for the Flyers this season. He has 38 goals and 270 points with the Flyers.