The Reds selected McCambley's contract from Triple-A Louisville on Tuesday.
The 27-year-old was acquired from the Marlins in exchange for Rece Hinds on May 21 and is now on the cusp of making his MLB debut. Across 30.1 innings at the Triple-A level this year, McCambley has a 2.37 ERA, 1.19 WHIP and 37:18 K:BB in 15 appearances (two starts).