Castleman released his debut album, Crazy as Me, on Rounder Records in 2000.

At the Grammy Awards in 2002, he won Best Country Song category as the writer of the song "The Lucky One," performed by Alison Krauss & Union Station.^[1][2]

Successful songs written by Castleman include Alan Jackson's "The Firefly's Song;" "Like Red on a Rose" (nominated for a Grammy Award in 2007 in the Best Country Song category); "Maybe I Should Stay Here," "Nobody Said That It Would Be Easy," and "Where Do I Go from Here? (A Trucker's Song)"; Alison Krauss & Union Station's "Doesn't Have to Be This Way," "Forget About It," "Gravity," "Let Me Touch You for Awhile," "Paper Airplane" and "Restless"; Chet Atkins's "Sneakin' Around," "Somebody Loves Me Now," "Take a Look At Her Now"; and Jon Randall 's "My Life."

• Galipault, Gerry (October 8, 2000). "Robert Lee Castleman Drives a Hard Musical Bargain". Pause & Play.