He began playing records in 1991 on the Funk Inc. show on 2-MBS FM, playing a mix of funk, jazz, soul, hip hop and house for over five years. During this time he also teamed up with Trevor Parkee for some small gigs, which soon led to a residency at the now legendary All Funked Up night at The Bentley Bar. Over the next five or so years Caldwell held residencies on six out of seven nights at the Bentley which enabled him to showcase his diversity, switching from retro to tribal/deep house sounds. He also began to play at the Funk Inc parties, always noted for bringing new flavours into the mix, moving on to notable residencies at Home and Chinese Laundry.

Nowadays Caldwell indulges his other musical passions - soulful house and techno - regularly playing peak sets at some of Sydney's biggest house events and has pitched his skills alongside dozens of internationals including Moodymann, Derrick Carter, Derrick May, Andy Weatherall, Gilles Peterson, Norman Jay, Thievery Corporation, James Lavelle, Jamie Liddel, Kid Koala, Sharon Jones, Fat Freddy’s Drop, Public Enemy, James Brown, Grace Jones, Todd Terje, Jazzanova and many more. He regularly plays outside Sydney at the cream of Australia's underground clubs and has also ventured overseas playing in Berlin, Barcelona, Czech Republic and Hong Kong.

He has released two mix CDs, the first with Ken Cloud - "DJ Excursions Vol.5" in 1998, the second with Mako - "Mixed Business" in 2003 and presented a Resident Advisor Podcast in late 2009.

Alongside his DJing, Caldwell co-promotes Mad Racket, a Sydney underground party institution which has toured the likes of Herbert, Jamie Liddel, Moodymann, Theo Parrish, Darshan Jesrani, Steve Bug, Swag, Charles Webster and Tom Middleton.

As a DJ, Simon Caldwell continues to push new ideas and influences while still being able to draw on the history of his expansive and discriminating record collection. Whether he's playing deep house, techno, ambient, soul, hip hop, bangin' Chicago house, Detroit electro or jazz, you can expect to hear the old alongside the new, but in the hands of Simon Caldwell, music is timeless.