"Mark gives us another quality left-handed arm in our rotation, and his experience and veteran leadership should benefit our clubhouse," Marlins manager Fredi Gonzalez said.
Hendrickson's deal is for $1.5 million, plus incentives.
Additionally, the Marlins signed left-handed pitcher Randy Williams to a Minor League contract with an invitation to big league camp, and infield prospect Gaby Sanchez also will be invited to Spring Training.
Hendrickson broke in with the Blue Jays in 2002, and the left-hander has also played for the Rays and Dodgers. He holds a career mark of 43-55 with a 5.21 ERA in 179 games, including 135 starts.
For Los Angeles last season, Hendrickson made 15 starts, and he logged 122 2/3 innings.
The addition of Hendrickson potentially gives the Marlins three left-handers in their starting rotation. The pitching staff also includes southpaws Scott Olsen and Andrew Miller.
Florida's 40-man roster now stands at 40, and currently an additional 29 players also have been invited to Major League camp when Spring Training opens next month.
A multisport star in high school, the 6-foot-9 Hendrickson attended Washington State University. He played parts of four seasons with four teams in the NBA: Philadelphia, Sacramento, New Jersey and Cleveland.
Williams, 32, spent last year in the Rangers' Minor League system. He has 38 games of Major League experience, all in relief, posting a 3-1 mark with a 6.68 ERA in stints with Seattle (2004), San Diego (2005) and Colorado (2005).
Sanchez, 24, was the Marlins' fourth-round Draft pick out of the University of Miami in 2005. A catcher in college, he has played mostly first base in the Minor Leagues, coming off a season in which he batted .279 with nine home runs, 40 doubles and 70 RBIs in 133 games at Class A Jupiter.