The Astros also announced on Thursday that former first-round picks Delino DeShields Jr. and George Springer would be going to Major League camp for the second consecutive year as non-roster invitees.
Houston has 58 players on its Spring Training roster, including 18 non-roster players.
Ankiel, 33, has hit 69 homers in 1,793 career Major League at-bats with St. Louis, Kansas City, Atlanta and Washington, where he spent the last two years. He possesses a tremendous arm, which is not surprising, considering he came up as a pitcher.
Ankiel won 13 games for the Cardinals, mostly from 1999 to 2001. He went 11-7 with a 3.50 ERA in 31 games (30 starts) in 2000, but his sudden inability to throw strikes forced him to try his hand as a hitter.
General manager Jeff Luhnow, who was with Ankiel in St. Louis for several years, thinks he brings plenty to the table.
"He can play all three outfield positions," Luhnow said. "He's got a plus-plus arm and plays good defensively. He's a left-handed power bat. In my time I overlapped with him at the Cardinals, he was a very special player. He had big-time power at Triple-A and got promoted to the big leagues and showed that power there. He's been inconsistent the last few years, but we really feel like this is a guy we want to take a chance on. He'll come into camp looking to make the club."
Both DeShields, 20, and Springer, 23, had outstanding Minor League seasons in 2012. DeShields, the Astros' first pick in the 2010 First-Year Player Draft, set an organizational record with 101 combined stolen bases at Class A Lexington (83) and Class A Lancaster (18) en route to being named the Astros' Minor League Player of the Year.
In 111 games playing second base at Lexington, DeShields hit .298 with 96 runs, 22 doubles, five triples, 10 homers, 52 RBIs and a .401 on-base percentage prior to being promoted to Lancaster. Springer, the Astros' No. 1 Draft pick in 2011, hit .318 with 10 triples, 22 homers, 82 RBIs and 28 steals in just 106 games as an outfielder at Lancaster.
Neither is expected to make the big league club this year.
The other non-roster players are left-handers Kevin Chapman and Sergio Escalona; right-handers Chuckie Fick, Edgar Gonzalez and Josh Zeid; outfielders Trevor Crow, Jake Goebbert, Marc Krauss and Che-Hsuan Lin; catchers Rene Garcia, Jason Jaramillo, Carlos Perez and Chris Wallace; and infielders Brandon Laird and Jose Martinez.