Ohlendorf was released by Kansas City on Wednesday after he opted out of his minor league deal Monday. He made eight spring training appearances, allowing six runs on nine hits and three walks in nine innings. Ohlendorf had 10 strikeouts.
The 33-year-old has played nine seasons in the majors. He has 80 career starts and 65 relief appearances.
Last season, Ohlendorf pitched for Texas and was used in late relief situations, finishing six games. He earned his only career save for the Rangers.
Ohlendorf has a 25-34 career record with a 4.84 ERA.
The Reds have several injuries on a young pitching staff.
Information from ESPN's Jerry Crasnick and The Associated Press contributed to this report.