He appeared with Ronson at the 2007 Glastonbury Festival where he climbed up on to the lighting rig of the John Peel stage during the performance of "Just", and also sang "California".

In 2010, he collaborated once again with Ronson on the album "Record Collection", on which Greenwald shares writing credits on six out of the eleven tracks.

At live shows, he was known for 1980s-style dance moves, which were inspired from watching David Byrne of Talking Heads.

He told PETA his reasons for going vegan: "In college I stopped eating red meat on a bet with my girlfriend at the time.

at the Disco members Ryan Ross and Jon Walker's new band, The Young Veins debut record, Take a Vacation!.

He is currently part of the group Phases (previously named JJAMZ), and signed to Warner Bros. Records.

JJAMZ was a band composed of Greenwald along with James Valentine (Maroon 5), Jason Boesel (Rilo Kiley/Conor Oberst), Michael Runion (solo), and Z Berg (The Like).

Signed to Warner Bros. Records, Phases is composed of Greenwald, Z Berg, Jason Boesel, and Michael Runion.

[4][5] In June 2020, it was confirmed that Greenwald and Australian actress Phoebe Tonkin were in a relationship.