Johnston worked briefly as a staff producer for Kapp Records, then for Columbia Records in New York, where he began producing a string of notable and highly influential albums (see list below). He was already producing Patti Page when in 1965 he was successful in gaining the assignment to produce Bob Dylan, followed by Simon & Garfunkel, the Pozo-Seco Singers, Johnny Cash, Flatt & Scruggs, and then Leonard Cohen. His style of production varied from a 'documentary' approach capturing a fleeting moment (exemplified by Dylan's albums and Cash's live albums) to providing subtle arrangements with strings, background vocals and seasoned session musicians (exemplified by Cohen's studio albums).