Ayestaran's illustrations appear in newspapers, magazines, advertising and books. His clients include Fortune, Wired, Variety, The Hollywood Reporter, The Boston Globe, Men's Health, The American Interest, D CEO, Orange, Jamie, Phill, Magazine, The Economist, El Comercio, Caribean Travel & Life, Bucknell Magazine, Tufts Magazine, Emory Health, Siempre Mujer, Montreal's Literature Festival, Marriott Alumni Magazine, Connecticut Magazine. In Spain his include La Vanguardia, Diario ABC, El Correo, Diario Público, Tiempo, Mía, Elkar, Turner, Bench, Cortefiel.
His work has been recognized by Communication Arts (Award of Excellence), 3x3 Conteporary Illustration (Merit), American Illustration (Selected), Lurzers Archive 200 best illustrators Worlwide and World Press Cartoon.
Iker resides in San Sebastian, Spain.