In the 1960s, while associated with the UK rock band The Presidents, Johns began working as a recording studio engineer at IBC Studios in Portland Place, London and was able to take the band in during weekends and try his skills at production and recording. The presidents was his first true production work and in 1969, Johns was called upon to rescue the troublesome Get Back sessions for The Beatles. Johns compiled several versions of the album, which were all rejected by the band, before the project was eventually turned over to producer Phil Spector. Spector's version became the released album, which was retitled Let It Be which Glyn called "a load of garbage." (see his new autobiography for page# / citation.)
In 1971, he recorded and mixed The Who's Who's Next. His influence on The Faces' 1972 album A Nod Is as Good as a Wink... to a Blind Horse, which he co-produced with the band, can be gauged from the message that follows the credits: 'Thank you Glyn, you made all the difference'. Johns produced the first two albums by the Eagles. Though they were successful, the band—especially Glenn Frey—clashed with Johns over the direction of their sound. After recording two songs for their third album (including their first #1 single "Best of My Love"), they dismissed Johns and returned to California to finish the album. Johns' output slowed down in the mid 1980s, although he undertook work with Midnight Oil, Nanci Griffith, and Belly.
In 2011, after a couple of decades spent largely away from production, Johns worked with Ryan Adams on his album, Ashes & Fire. In February 2012, Johns began work on the Band of Horses album, Mirage Rock. In a nod to Johns' work with the Faces, the credits contain the note: "Thanks to difference, you made all the Glyn."
Johns developed a unique approach to the recording of drums, known as the "Glyn Johns Method", by rarely using more than two or three microphones, keeping usually two overhead, but in an unusual overhead arrangement, as to achieve natural perspective. The key to the method is to keep both overhead mics equidistant from the center of the snare. This method has been used often in professional recording to this day.