Born and raised in Whangarei, New Zealand, Milo Cawthorne developed a love for acting at a young age and participated in several productions in the local community theatre. But his talents took him further than just his hometown as he began appearing in several children's television shows, even starring in "P.E.T. Detectives" (2003) as Evan. Still, he made his home on stage and even performed as part of New Zealand's Young Shakespeare Company at the Globe Theatre in London.

After unsuccessfully attempting to enroll in drama school and working as a pizza delivery boy for about a year, Cawthorne landed the role of bumbling ex-cartel member Ziggy Grover, Ranger Operator Series Green, on "Power Rangers RPM" (2009), which gave him exposure to a much larger audience than what he had been used to. Following this, he returned to the stage and participated in several theatre productions, including "The History Boys" (2009) with the Peach Theatre Company, and "360" (2010) for the New Zealand International Arts Festival. He also appeared in an episode of the miniseries "Underbelly NZ: Land of the Long Green Cloud" (2011).