Born in Cleveland, Ohio on October 24, 1952, Weber began writing while in fifth grade. Some of Weber's first jobs within the writing/advertising world began after high school when he worked as copywriter, typesetter, proofreader, and paste-up artist. He later earned an undergraduate degree and M.A. in history.
Weber's first published novels grew out of his work as a wargame designer for the Task Force game Starfire. Weber wrote short stories set in the Starfire universe for Task Force Games' Nexus magazine, and he wrote the Starfire novel Insurrection (1990) with Stephen White after Nexus was canceled. This book was the first in a tetralogy that continued through their last collaboration, The Shiva Option (2002), which made The New York Times Best Seller List.
Weber was influenced by C. S. Forester, Patrick O'Brian, Keith Laumer, H. Beam Piper, Robert A. Heinlein, Roger Zelazny, Christopher Anvil and Anne McCaffrey He has in turn influenced such writers as Steve White, John Ringo, Eric Flint and Walter Jon Williams.
Weber's novels range from epic fantasy (Oath of Swords, The War God's Own) to space opera (Path of the Fury, The Armageddon Inheritance) to alternate history (1632 series with Eric Flint) and military science fiction with in-depth characterization.
A lifetime military history buff, David Weber has carried his interest of history into his fiction. He is said to be interested in most periods of history, with a strong emphasis on the military and diplomatic aspects.
Weber prefers to write about strong characters. He develops a character's background story in advance in considerable detail because he wants to achieve that degree of comfort level with the character. Weber has said he writes primarily in the evenings and at night.
Weber says he makes an effort to accept as many invitations to science fiction conferences and conventions as he can, because he finds the direct feedback from readers that he gets at conventions extremely useful. He makes a habit of Tuckerizing people from fandom, particularly in the Honor Harrington books (see, e.g., Jordin Kare).
In 2008, Weber donated his archive to the Department of Rare Books and Special Collections at Northern Illinois University.
Weber and his wife, Sharon, live in Greenville, South Carolina with their three children and "a passel of dogs".
In a video interview available on YouTube, Weber said he is a United Methodist lay preacher, and that he tries to explore in his writing how religions (both real-life and fictional) can be forces for good on the one hand, and misused to defend evil causes on the other.
Weber belongs to the American Small Business Association, the Science Fiction and Fantasy Writers of America ("SFWA"), and the NRA.