During 1989–1993 and 1998–2002 Garrett was the President of the Australian Conservation Foundation, whilst during 1993–1998 he was on the International Board of Greenpeace. In 1990 Midnight Oil played an impromptu lunchtime set in front of Exxon headquarters in New York with a banner reading, "Midnight Oil Makes You Dance, Exxon Oil Makes Us Sick," protesting the Exxon Valdez oil spill the previous year.