A member of the Liberal Party, Garrett served on the Victorian Legislative Council for eighteen years, and was knighted in 1973.
Flying as the chief pilot for the company, Garrett ran the first Territory-wide mail route, and provided the air links between Darwin and other townships in the territory.
When World War II broke out, Garrett was called up into the Royal Australian Air Force.
After the war, Garrett took his earlier love of photography and set up a successful business in Doncaster, manufacturing photographic chemicals.
It was around this time that Garrett also began to dabble in politics, sitting on the council of the Shire of Doncaster and Templestowe for six years.