He came to prominence as an artist in the mid-1980s, as part of the generation of Neo-Conceptualist artists that first exhibited in New York’s East Village, including Jeff Koons, Haim Steinbach, Sarah Charlesworth, Annette Lemieux, Steven Parrino, Phillip Taaffe, Gretchen Bender, and Meyer Vaisman. Halley's paintings explore both the physical and psychological structures of social space; he connects the hermetic language of geometric abstraction—influenced by artists such as Barnett Newman and Ellsworth Kelly—to the actualities of urban space and the digital landscape. In the 1990s, he expanded his practice to include installations based around the technology of large-scale digital prints.