The option was worth $12.75 million. The Phillies and Burnett declined their $15 million mutual option for 2015 on Sunday, for which Burnett received a $1 million buyout.
"We do expect that he will pitch in 2015. For a contender," Burnett's agent told FOX Sports' Ken Rosenthal.
Burnett spent the 2014 season in Philadelphia. He was diagnosed with an inguinal hernia in April and pitched with it the rest of the season.
In August, the 37-year-old said he would probably retire at the end of the season, but softened that stance a week later, saying it would depend on how he and his family feel.
In 2014, Burnett went 8-18 with a 4.59 ERA and 190 strikeouts in 213.2 innings. He started 34 games, which was tied for the most in MLB and walked a major league-leading 96 batters.
The veteran has pitched in the majors for 16 years and holds a 4.04 career ERA.
Philadelphia went 73-89 in 2014, finishing in last in the NL East.
- Molly Geary