Otto is the son of first-generation Greek immigrants, and was born and raised in Sydney, New South Wales. He completed a degree in creative writing and literature before studying acting at NIDA (National Institute of Dramatic Art), graduating in 2000.
Otto had a guest role in Australian children's television series Outriders in 2001 followed by a leading role in drama series Young Lions in 2002 as Justin Carmody.
Otto appeared in the 2003 movie The Matrix Reloaded. This was followed by X-Men Origins: Wolverine, The Rage in Placid Lake and Beautiful.
In 2009, Otto played the lead role of Charles Darwin in drama-documentary Darwin's Brave New World.
He appeared in television series Dance Academy in 2010 as Adam the Psychologist and in 2011 had a guest stint on Home and Away as Detective Robert Robertson. This was followed by guest roles in television series Rake, The Doctor Blake Mysteries and Serangoon Road.
In 2013, he appeared in the mini-series Paper Giants: Magazine Wars as Peter Dawson and in the 2014 telemovie Carlotta as Christopher.
In 2014 to 2017 he joined the cast of Wentworth in the role of transwoman prison inmate Maxine Conway (formerly Max).