Financial terms were not disclosed.
Comrie was acquired from the Edmonton Oilers on Tuesday for former first-round pick Jeff Woywitka and two draft picks.
The team announced Comrie's signing before Saturday's game against the New York Islanders.
Philadelphia entered Friday night's games with the most points in the league, but had lost its last three games, all at home.
The Oilers received a first-round pick in the 2004 entry draft and a third-round choice in the 2005 draft from the Flyers. Comrie has not played this season because of a bitter contract dispute with Edmonton that resulted in his departure.
Oilers general manager Kevin Lowe said earlier this week that Comrie's decision not to re-sign with Edmonton wasn't a financial one.
The Oilers thought they had a deal last week to send Comrie to Anaheim, but it was held up by Lowe, who wanted Comrie to pay the club $2.5 million first.
Entering this season, the Oilers offered Comrie the minimum raise allowed, which he rejected. The Oilers would not negotiate, and Comrie asked to be traded.
In 69 games for the Oilers during the 2002-03 season, Comrie had 20 goals and 31 assists for 51 points. In 192 career NHL games over three seasons with Edmonton (2000-01 through 2002-03), Comrie has 61 goals and 72 assists for 133 points.
He set career highs for goals in a season (33), points in a season (60) and games played in a season (82) during the 2001-02 season. Comrie was selected by the Oilers out of Michigan in the third round of the 1999 entry draft.
Information from The Associated Press was used in this report.