O'Regan got his start in music as one of the founding members of post-punk quartet the D'Urbervilles (renamed Matters in 2011),[1] where he was known as John O alongside Tim Bruton, Kyle Donnelly and Greg Santilly.

"[4] His first release was a limited edition split 7-inch vinyl single titled "All Yr Songs" that was distributed through his own boutique label Hype Lighter in August 2009.

When word of the slip up caught on throughout the blogosphere Sony/BMG withdrew its claim and issued O'Regan and video director Colin Medley a formal apology.

[7] In March 2010, Diamond Rings released a new 7-inch single with German label Tomlab entitled "Wait & See", which features backing vocals from Toronto musician Gentleman Reg.

[9] His next single was a 12-inch Chicago House inspired dance track titled "Show Me Your Stuff", which was released in June 2010 on Fucked Up guitarist Mike Haliechuk's One Big Silence imprint.

The corresponding video also featured a cameo from Fucked Up vocalist Damian Abraham and has drawn comparisons to disparate artists such as Klaus Nomi, Nirvana, and Britney Spears[10] His debut full-length album, Special Affections, was released in North America on October 25, 2010, by Montreal's Secret City Records.

[11] Lead single "Something Else" was released a month prior and features a cover of the Milla Jovovich song "The Gentleman Who Fell," with string arrangements by Canadian musician and Polaris Prize winner Owen Pallett.

Following the album release Diamond Rings opened for Swedish pop star Robyn for the duration of her North American Body Talk tour in the winter of 2011.

[15] He has not released new music in several years and has instead worked as an art director in film, with credits including Operation Avalanche, Mean Dreams, Giant Little Ones, and Castle in the Ground.