Besides "I Can See Clearly Now," Nash recorded several hits in Jamaica, where he travelled in early 1968, as his girlfriend had family links with local TV and radio host and novel writer Neville Willoughby. Nash planned to try breaking the local rocksteady sound in the USA. Willoughby introduced him to a local struggling vocal group, The Wailers. Members Bob Marley, Bunny Wailer and Peter Tosh introduced him to the local scene. Nash signed all three to an exclusive publishing and recording contract with his JAD label and financed some of their recordings, some with Byron Lee's Dragonaires and some with other local musicians such as Jackie Jackson and Lynn Taitt. None of the Marley and Tosh songs he produced were successful. Only two singles were released at the time: "Bend Down Low" (JAD 1968) and "Reggae on Broadway" (Columbia, 1972), which was recorded in London in 1972 on the same sessions that produced "I Can See Clearly Now." The I Can See Clearly Now album includes four original Marley compositions published by JAD: "Guava Jelly", "Comma Comma", "You Poured Sugar On Me" and the follow-up hit "Stir It Up". "There Are More Questions Than Answers" was a third hit single taken from the album.
Nash was also active as a composer in the Swedish romance Vill så gärna tro (1971) in which he portrayed Robert. The film soundtrack, partly instrumental reggae with strings, was co-composed by Bob Marley and arranged by Fred Jordan.
JAD Records ceased to exist in 1971, but it was revived in 1997 by American Marley specialist Roger Steffens and French musician and producer Bruno Blum for the "Complete Bob Marley & the Wailers 1967-1972" ten-album series for which several of the Nash-produced Marley and Tosh tracks were mixed or remixed by Blum for release. Nash's biggest hits were the early reggae (rocksteady) tunes "Hold Me Tight" (a #5 hit in the U.S. and the UK) and "Stir It Up", the latter written by Bob Marley prior to Marley's international success. In the UK, his biggest hit was with the song "Tears On My Pillow" which reached number one in the UK Singles Chart in July 1975 for one week. After a hit version of Sam Cooke's "What A Wonderful World" and "Let’s Go Dancing" in 1979, for many years he seemed to have dropped out of sight; however, in May 2006 he was singing again at Sugar Hill recording studio in his native Houston. Working with chief engineer Andy Bradley, he began the work of transferring analog tapes of his songs from the 1970s and 1980s to Pro Tools digital format. These mixes are highly anticipated, as current CD recordings available of Johnny's hits were mastered with tracks missing, some also recorded at incorrect levels, when compared to the original single 45 rpm versions.