He funded his early writing career by producing term papers for college students, which gained him some notoriety when he described this experience in an essay for Drexel University's online magazine The Smart Set.

He is also a graduate of the MFA program in creative and professional writing at Western Connecticut State University, which he attended only after publishing a number of books, short stories, and articles.

Mark Halcomb of the Village Voice reviewed the book and its peculiar meshing of Lovecraft and Kerouac, writing, in part, "In fact, Kerouac's 'bebop prosody' and the Cthulhu mythos dovetail nicely, and what seems at first like literary stunt-casting actually gives Mamatas room to recast the Beats' fall from grace in fanciful terms unhindered by their tricky psychology, the strictures of reality and realism—or lingering platitudes.

Ed Park, writing for his online The Los Angeles Times review column, described Mamatas's Under My Roof—a short novel about the formation of a microstate on Long Island—as an "accurate, fast-moving satire that transcends mere target shooting by virtue of its narrator, Daniel’s 12-year-old son Herbie".

[8] A starred review in Publishers Weekly for the same title also highlighted the satirical elements in the work, declaring: "A big-bang ending caps the fast-paced novel, and there's much fun to be had watching Mamatas...merrily skewer his targets.

Essays from The Smart Set, Village Voice, The Writer and Tim Pratt's fanzine Flytrap were compiled, along with original material, into the writing handbook Starve Better in 2011, and published by Apex Publications[16] His essay "The Term Paper Artist" originally from The Smart Set, about his experiences as an academic ghostwriter for pay, has been discussed on National Public Radio and reprinted in a pair of textbooks, both published by Nelson Education.