The Ravens tried out Painter along with former Ravens starter Kyle Boller and former Pittsburgh Steelers backup Dennis Dixon.
Painter is slated to compete with former sixth-round draft pick Tyrod Taylor for the backup job behind Joe Flacco.
The transaction allows Painter to play for Jim Caldwell, his former coach in Indianapolis, who was hired as the Ravens' quarterbacks coach this offseason.
Last season, Painter started eight games for the Colts with Peyton Manning out for the entire year after undergoing neck surgery.
However, Painter won no games as he passed for 1,541 yards, six touchdowns and nine interceptions for a 66.6 quarterback rating.
The former sixth-round draft pick from Purdue was ultimately benched and replaced by Dan Orlovsky.
For more coverage of the NFL, go to profootball.scout.com.
Follow me on Twitter: @RavensInsider
Want more in-depth coverage on your favorite NFL team? Click here and get started today.