[7][8][9] Short fiction by Williamson includes the story "Soft Casualty", an exploration of psychological warfare which won a readers' choice award organized by Baen Books.

[15][18] Williamson's military career included service with the United States Air Force in deployments in support of Operation Iraqi Freedom.

[18][20] Freehold tells the story of Kendra Pacelli, a young soldier who begins the book in the service of a world-dominant, authoritarian United Nations.

[22] Don D'Ammassa criticized Freehold as a political tract with an oversimplified and unrealistic view of humanity calling it a "very long but frankly not very entertaining diatribe".

[23] Michael M. Jones of SF Site conversely called Williamson's portrayal of a libertarian society "sound and believable" and described the book as "a satisfactory debut".

[25] Carolyn Cushman of Locus noted heavy emphasis on the exposition of Libertarian ideology with plotting and pacing taking a back seat but described the novel as "amazingly entertaining".

[28] The novel Do Unto Others (2010) made the Wall Street Journal best-seller list in hardcover science fiction[29] and Angeleyes (2016) sold in more than 100,000 copies.

[3] The book is set in Williamson's Freehold universe and he also wrote or co-wrote five of its 16 stories; other contributors included Larry Correia, Tony Daniel, and Tom Kratman.

[5][6] Among works not set in the Freehold universe is Williamson's second novel, The Hero (2004), which was written with John Ringo and made the Locus Bestseller list in February 2006.

[15] Williamson has contributed short fiction to numerous anthologies, including many which take place in the Valdemar and Elemental Masters shared universes created by Mercedes Lackey.

[35] In 2015, Baen Books released an anthology, The Year's Best Military SF & Space Opera, which was described by Don Sakers of Analog as "long overdue".

[44] John Clute comments in The Encyclopedia of Science Fiction that a pattern running through the works of Williamson is a fight to maintain freedom against external enemies with the heroes adhering to libertarian principles.

This depiction of the United Nations has parallels in the Marine in Space series by Ian Douglas and in the works of Tom Kratman[46]: 219–220  and is reflective of a negative right-wing popular opinion on the institution.