Following a seven-week trial, a jury found the firm of Anchin, Block & Anchin acted negligently and in breach of its fiduciary duties in managing the financial affairs of Cornwell and her partner, McLean Hospital neuroscientist Dr. Staci Gruber.
"We are deeply gratified by this victory," Cornwell said in a statement. "This case was about a lot more than financial mismanagement. It is our belief that Anchin, Block & Anchin not only took advantage of us, they also tried to damage our reputations and put us in legal jeopardy."
The defendants told the Boston Globe they would explore an appeal of the verdict.
Cornwell is famous for penning the blockbuster Kay Scarpetta murder mysteries.
2014: NFL Cheerleaders [PHOTOS]
Kelly Ripa's penthouse sells for $20M