[2] Robertson also wrote and directed two episodes of the Logie Award winning crime drama Romper Stomper, and appeared earlier in his career as an actor in Shakespearean theater and several television productions including The Tribe and Being Eve, describing how his acting work "funded his early filmmaking".

[3] Born in Wellington, New Zealand, but moving to Auckland at a young age, Robertson grew up in Devonport and attended Takapuna Grammar School, where he first started acting in Shakespeare productions and musicals.

In 2002 Robertson was cast for two seasons in UK show The Tribe, a post apocalyptic series about a virus that has wiped out all adults, leaving only young people to fight amongst each other.

[10] It was picked up by Rialto Distribution for a New Zealand wide theatrical release from January to March 2010 to strong reviews, but low box office.

[11] In 2010 Robertson started work on his second feature film, The Dark Horse, based on the life story of Genesis Potini, a Māori chess player who suffered from severe bipolar.

The New Zealand Herald rated it 5 stars, calling it "a great, deeply affecting movie", with "brave, assured and layered directing" and praising the "towering performance of Cliff Curtis".