Born in Iowa City, Iowa on May 9, 1968, and raised in Mount Vernon, Iowa. Harman attended St. John's College in Annapolis, Maryland, receiving his B.A. in 1990. He then pursued graduate study under philosopher Alphonso Lingis at Penn State University, receiving his M.A. in 1991. Transferring to DePaul University in Chicago, he received his Ph. D. there in 1999. While in Chicago, he worked briefly as a sportswriter for sportsextra.com (now defunct). Since 2000, he has been a member of the Department of Philosophy at the American University in Cairo.

Through an interpretation of the tool-analysis of Heidegger's Being and Time, Harman sets out to develop what he calls an object-oriented philosophy. Taking the tool-analysis as the defining moment in twentieth-century philosophy, Harman finds in Heidegger the roots of a metaphysics of things which does justice to the things themselves. Although working from within it, he finds the broad history of phenomenology to be deficient in that it constantly subordinates the independent life of objects to our (human) access to them. Against the Kantian tradition, his object-oriented approach considers the neglected real life of objects to be fertile ground for a resurgent metaphysics. Emphasizing the notions of substance and occasional cause (see occasionalism), he affirms the autonomy of objects while aiming to 'allude' to their shadowy underground life and covert interactions by means of metaphor.

According to Harman, everything is an object, whether it be a mailbox, electromagnetic radiation, curved spacetime, the Commonwealth of Nations, or a propositional attitude. Expressing strong sympathy for panpsychism, Harman proposes a new philosophical discipline called "speculative psychology" dedicated to investigating the "cosmic layers of psyche" and "ferreting out the specific psychic reality of earthworms, dust, armies, chalk, and stone" (Harman 2009: 213).

Cutting across the phenomenological tradition, and especially its linguistic turn, Harman deploys a brand of metaphysical realism that attempts to extricate objects from their human captivity and metaphorically allude to a strange new subterranean world of objects.