De Farfalla originally joined Opeth in 1991 when its lineup was David Isberg on vocals, Mikael Åkerfeldt and Kim Pettersson on guitar, and Anders Nordin on drums. He replaced Nick Döring on bass for one show and quit immediately afterwards. Opeth recruited Peter Lindgren to replace him for their next show, and then Stefan Guteklint after Lindgren moved to guitar. In 1994, Opeth was approached for signing by Candlelight Records, and fired Guteklint. De Farfalla rejoined Opeth initially as a session bassist for their first album Orchid (1995), but subsequently became an official member again. After touring in support of their second album Morningrise (1996), De Farfalla was fired by Åkerfeldt who cited that De Farfalla was not a good fit. De Farfalla wanted the bass to have a more prominent role in the music of Opeth, something Åkerfeldt felt uncomfortable with.
Departure from the general mix, aesthetic, and overall sound of Opeth's first two albums is often attributed partly to the recruitement of bassist Martin Mendez and drummer Martin Lopez, although Mendez did not contribute or record any basslines for Opeth's next release (1998's My Arms, Your Hearse). (Anders Nordin quit Opeth to move to Brazil days after De Farfalla was fired.) If Opeth's sound is describable as having jazz influence, it is most prevalent on their first two albums (those De Farfalla and Nordin contributed to), their fourth (Still Life) being an exception.
Johan De Farfalla used to work as a teacher at Storviks Folkhögskola until 27 January 2012. He lives with his wife and 3 children.