In 2017, he began playing Matthew Goddard in A Place To Call Home, and he joined the cast of Neighbours in the recurring role of Vance Abernethy in 2019.

It was not long after leaving the Mona Vale school that Coleby performed in his first professional role in the mini series Tanamera – Lion of Singapore in 1989.

In his third year in 2000, Coleby travelled to Singapore, Los Angeles, New York and Stratford on Avon performing the title role of Lewis in Louis Nowra's Cosi as part of the university's first ever world tour.

In 1999, before leaving drama school, Coleby co-starred with the Irish actor Eoin Moloney in the TV movie Sabrina Down Under, filmed on Hamilton Island.

He was then cast in episodes of Always Greener (2002) and Water Rats (2000) before landing the role of series regular Scott Zinenko on the medical drama All Saints, which he played from 2001 to 2004.