After graduating from the Royal College of Art in London, in 1964 BILLY APPLE moved to New York where he continued to produce pop-related paintings and objects before developing a body of neon sculptures. By 1969 Apple had shifted to a more conceptual and process-oriented practice. A major survey of Apple's work, which brought together his pop and conceptual works from 1960 to 1974, was staged at the Serpentine Gallery in London in 1974. Apple exhibited regularly at various venues in New York's alternative art scene and remained in New York until 1990, continuing to exhibit his work in various venues, including Leo Castelli Gallery. He also made two extended tours to New Zealand in 1975 and 1979-80, producing a string of site-specific installations in dealer and public galleries throughout the country.

Since the early 1980s Apple has complemented his installation practice with text-based works that draw attention to the art system and highlight the network of relations that operate between artist, dealer, and collector. Billy Apple became a registered trademark in 2007 to formalise his art brand status and continues to develop projects that address this, for example working with apple growers over the production and branding of a new apple cultivar and a collaborative art/science project, The Immortalisation of Billy Apple®, in which cells from his blood have been virally transformed to create a cell line that will live outside the body for use in studies like cancer research.

A large scale public art work by Apple was commissioned for the city of Auckland for the 2011 IRB Rugby World Cup which lies outside Eden Park, Kingsland. Based in Auckland since the 1990s, Apple exhibits regularly in dealer, public and artist-run galleries throughout New Zealand and in Australia, and his works have been included in major international and national touring exhibitions. These include: Toi Toi Toi: Three Generations of New Zealand Artists (Kassel & Auckland, 1999); Global Conceptualism: Points of Origin (New York, 1999); Kronos + Kairos: die Zeit in der Zeitgenössischen Kunst, (Kassel, 1999); Shopping: A Century of Art and Consumer Culture (Frankfurt & Liverpool, 2002-3); American Supermarket (Pittsburgh, 2002), and Art of the '60s from Tate Britain (Auckland, 2006). In 2009 a second major survey exhibition of Apple's work was staged in two parts at Witte de With, Center for Contemporary Art in Rotterdam (Billy Apple®: A History of the Brand and Revealed/Concealed). In New Zealand aspects of his career have been reevaluated in exhibitions such as Billy Apple: New York 1969-1973 (Wellington 2009).