After serving in the U.S. Navy, Johnston returned to Fort Worth, Texas, where he and his mother collaborated on songwriting for rockabilly artist Mac Curtis and others.

[4] In later years, Johnston claimed that songs still credited to his wife Joy Byers were actually co-written, or solely written by himself.

[6] In 1965 he was successful in gaining the assignment to produce Bob Dylan,[2][7] followed by Simon & Garfunkel,[2] Johnny Cash, Flatt & Scruggs, and then Leonard Cohen.

In 1979, Johnston produced an album with the San Francisco band Reggae Jackson, titled Smash Hits that featured Jimmy Foot, Cheryl Lynn, Kenneth Nash, and Wayne Bidgell (the low voice heard on Jimmy Cliff's "Bongo Man" track).

Billboard magazine's "Pop Pick of The Week", the album's release was plagued with distribution difficulties.

During a period of financial difficulty, when he was under scrutiny from the IRS, Johnston moved to Austin, Texas, and did no record production for some time.

which featured numerous guest stars including Paul Simon, George Harrison and Ringo Starr, as well as unreleased recordings of Perkins' "Blue Suede Shoes" by John Lennon and Jimi Hendrix.

The final project Johnston worked on was Evolution: Live at the Saxon Pub which he co-produced for Austin band Hector Ward and The Big Time in 2015, which was released in 2016.