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 $175,000 and she would be barred from the following U.S. Open.
Babcock said the previous highest fine for a Grand Slam offense was about $48,000 to Jeff Tarango in the 1990s.
Williams lashed out at a lineswoman after a foot-fault call at the end of her U.S. Open semifinal loss to eventual champion Kim Clijsters.
Williams earned $350,000 by reaching the semifinals, part of her more than $6.5 million in prize money in 2009, a single-season record for women’s tennis. Her career prize money tops $28 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 $10,000 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.