Babcock's decision was to be formally released later Monday.
He said Williams faces a "probationary period" at Grand Slam tournaments in 2010 and 2011.
If she has another "major offense" at a major championship
in that time, the fine would increase to USD175,000 and she would be barred from the following US Open.
Babcock said the previous highest fine for a Grand Slam offense was about USD48,000 to Jeff Tarango in the 1990s.
Williams lashed out at a lineswoman after a foot-fault call at the end of her US Open semifinal loss to eventual champion Kim Clijsters.
Williams earned USD350,000 by reaching the semifinals, part of her more than USD6.5 million in prize money in 2009, a single-season record for women's tennis. Her career prize money tops USD28 million.
The American is an 11-time Grand Slam singles champion and ended the 2009 season at No. 1 in the WTA rankings.
Williams' profanity-laced, finger-pointing outburst drew a USD10,000 fine from the U.S. Tennis Association in September — the maximum onsite penalty a tennis player can face. But because it happened at a Grand Slam tournament, Babcock was charged with investigating whether further punishment was merited.
He concluded that Williams violated the "major offense" rule for "aggravated behavior." The Grand Slam committee — with one representative from each of the sport's four major championships — approved his decision Saturday.
Babcock said Williams has been informed of the ruling. She has been in Barbados for an exhibition tournament, and her agent did not immediately reply to a request for comment Monday.