Raised in Virginia, New Mexico, and Washington, D.C., Jennings grew up listening to everything from classical music and big-band swing to country music and rock & roll. Although he took piano and trumpet lessons as a youngster, he steered toward the guitar after hearing the Beatles. His performing debut came with a rock band in the sixth grade, and he continued to perform in the 1970s with Bill Holland & Rent's Due and Big Yankee Dollar, a group that mostly played his original songs.

Although he concentrated on writing advertising jingles in the early '80s, Jennings' musical career took off after Bill Danoff (of the Starland Vocal Band) introduced him to Mary-Chapin Carpenter. Performing together in the Washington, D.C., area, Jennings and Carpenter began to garner attention. An album recorded to be sold at their shows was reissued by Columbia Records as Carpenter's 1987 debut album, Hometown Girl.

Jennings took a temporary hiatus from Carpenter's band in 1993 and began work on his solo album; co-produced with Bob Dawson, Buddy was completed three years later. Jennings has remained one of Washington, D.C.'s most accomplished musicians, and has received area music awards (Wammies) as Producer of the Year (1987, 1989, 1991, and 1995), Best Folk/Bluegrass Instrumentalist (1991), Best Folk/Bluegrass Male Vocalist (1991), Best Contemporary Folk/Irish Instrumentalist (1992), Best Contemporary Folk/Irish Male Vocalist (1992), and Video of the Year ("Everybody Loves Me," 1997). I Belong to You followed in 1998.