Brown, 27, made his Major League debut this year with the Cards, batting .182 (4-for-22) in 11 games. Brown spent the majority of the season at Triple-A Memphis, where he hit .284 with 20 home runs and 73 RBIs in 107 games.
The Cardinals designated Brown for assignment before the National League Championship Series to make room for right-handed reliever Lance Lynn, who was coming off the 60-day disabled list. Lynn has pitched in the first two games of the NLCS.
A former standout at the University of Nebraska, Brown has played some third base and first base in his Minor League career. The Cards selected Brown in the 18th round of the 2007 First-Year Player Draft.
The addition of Brown brings the number of players on the Rockies' Major League roster to 36, four below the limit.
Thomas Harding is a reporter for MLB.com. Read his blog, Hardball in the Rockies, and follow him on Twitter @harding_at_mlb. This story was not subject to the approval of Major League Baseball or its clubs.