Friday's ruling in U.S. District Court in San Jose, Calif., said Adam Guerbuez and his company, Atlantis Blue Capital, violated the federal CAN-SPAM Act and must pay $436 million each in statutory damages and aggravated statutory damages.
Between March and April of this year, Guerbuez delivered more than four million spam messages to Facebook users in California, according to a complaint filed by Facebook.
The spam, which arrived as an inbox message, or a "wall" post, appeared like it was coming from legitimate Facebook account holders because Guerbuez and his co-conspirators tricked users into giving up their login details through methods such as phishing.
The junk messages hawked items, such as legal marijuana, male-enhancement pills and sexually oriented material, according to the complaint.
Facebook said it suffered harm to its reputation and the spam "tainted" the user experience for some of its 90 million active members.
Max Kelly, Facebook's director of security, said he doubted Guerbuez would be able to come up with the money, but the judgment was a victory nonetheless.
"Does Facebook expect to quickly collect $873 million and share the proceeds in some way with our users?" Kelly wrote Monday on The Facebook Blog. "Alas, no...But we are confident that this award represents a powerful deterrent to anyone and everyone who would seek to abuse Facebook and its users."
Guerbuez could not be reached for comment on Tuesday.