The Milk moviemaker is expected to accept the Visionary Award at the event, which runs from 17-28 November (10).
Created in 2004, the prize honours "visionaries in modern film".
This year (10), festival bosses are hailing Van Sant's works as "a celebration of film art". His noted film credits include Drugstore Cowboy, My Own Private Idaho, To Die For and Finding Forrester, among others.
The filmmaker joins rank of past Visionary Award recipients including Wong Kar Wai, Todd Solondz, Wes Anderson, Terry Gilliam and Luc Besson.