Robert Grilley was born in Beloit, but spent most of his childhood in Lancaster and Madison. He graduated from the University of Wisconsin in 1942. Pursuing his lifelong love of airplanes, he received his pilot's license through the Civilian Pilot Training Program in 1940 and remained a pilot until age 80. After graduation, he enrolled as an aviation cadet and became a B-17 Navigator during WWII (8th Air Force), flying 30 missions over Germany. Upon returning to Madison after WWII, he earned a master's degree and joined the UW Art Department faculty in 1945, where he taught life drawing and painting for 42 years.
Grilley was a respected figure painter, and later in his career chose to focus much of his work on family and friends. He completed several commissioned portraits of prominent Wisconsin leaders and is represented in permanent collections of the Butler Institute of American Art, De Beers Collection, Wichita Art Museum, Nelson Rockefeller Collection, Wustum Museum of Fine Arts, Krannet Art Museum, Madison Museum of Contemporary Art, UW Memorial Union and Wisconsin Historical Society.
Kohler Foundation has acquired two of Robert Grilley's paintings from his family and they are now in the permanent collection of the Chazen Art Museum in Madison, Wisconsin.