Aghayan received a Tony Award nomination for Applause. His other Broadway credits include Vintage 60, The Egg, Lorelei, and the 1971 revival of On the Town.
Aghayan designed numerous film and television programs including Matinee Theater, The Judy Garland Show, Dr. Doolitle, Caprice, Lady Sings the Blues, and Funny Lady. He received three Emmy Awards, three Oscar nominations, and numerous other honors for his work.
He designed for many of the world's biggest stars, including Julie Andrews, Fred Astaire, Pearl Bailey, Lucille Ball, Diahann Carroll, Cyd Charisse, Bing Crosby, Doris Day, Sammy Davis, Dick Van Dyke, Mitzi Gaynor, Betty Hutton, Danny Kaye, Peggy Lee, Shirley MacLaine, and Leslie Uggams.
He is survived by his longtime partner, designer Bob Mackie.