His first work dates back to 1933 in a book published about Maltese folklore by Professor Arnaldo Fabriani.
Apap managed to get a painter's scholarship from the School of Art in 1937 at the Accademia di Belle Arti in Rome, where he eventually spent most of his life.
[4] In 1964, Willie Apap took part in an exhibition of Sacred Art at the L'Agostiniana Gallery, Rome.
His works then appeared in a collective exhibition, in July 1972, of Sacred Art at St. John's Co-Cathedral, Valletta.
Princess Anne, Lord Mountbatten of Burma, King Vittorio Emanuele III of Italy, and the S.M.O.M.