Asays the judge awarded Mills a lump sum of $33 million plus assets she currently holds worth $15.6 million.
"I'm so, so happy with this," Mills told reporters following the closed hearing.
British law dictates that divorce cases are heard in private, and Judge Hugh Bennett delivered his ruling at a closed-door hearing at London's Royal Courts of Justice.
CBSNews correspondent Charlie D'Agata, who was at the London courthouse, said the figure was twice what Sir Paul had offered, but only about a third of what Mills wanted.
Mills had sought almost $250 million, while McCartney had said she should receive $31.6 million, including her own assets, which the court assessed at $15.6 million.
Judge Hugh Bennett found that the total value of all of McCartney's assets, including his business assets, was about $800 million. He said there was no evidence to support the widely published figure that was more than twice as much.
While the ex-Beatle left court without facing the cameras, D'Agata reported, Mills attacked his lawyers for their courtroom tactics - saying they played dirty, and called her names.
"I'm so glad it's over," Mills said at her impromptu news conference.
"It was an incredible result in the end to secure mine and my daughter's future and that of all the charities that I obviously plan on helping and making a difference with because you know it has been my life for 20 years," she said.
"Obviously the court do not want a litigant in person to do well, it's against everything that they ever wish, so when they write the judgment up they're never going to make it look in favor.
McCartney, wearing a dark suit and a black and white scarf, was the first to arrive for today's session, followed five minutes later by Mills, who sported a blue-and-brown pantsuit.
McCartney, 65, and Mills, 40, went to court last month to decide on Mills' share of his fortune, which had been estimated at as much as $1.6 billion. Media reports have suggested McCartney offered his wife around $50 million and that she was seeking at least double that amount.
The settlement has been a long time coming for the couple, who separated two years ago, after four years of marriage. At the time, they said the parting was "amicable" and insisted "both of us still care about each other very much."
But the split has grown fractious since McCartney filed for divorce alleging his wife's "unreasonable behavior."
Mills - a former model whose left leg was amputated below the knee after a motorcycle accident in 1993 - claimed McCartney had failed to protect her and their daughter from slander, death threats and other abuse, and accused the media of persecuting her. In November, Mills said she had been "treated worse than a murderer or a pedophile," despite years of work for land mine victims and animal welfare charities.
When the couple and their lawyers appeared for a six-day hearing before Judge Bennett last month, photographers craned to catch a glimpse of them entering the grand, neo-Gothic court building, and reporters huddled outside the courtroom door.
But few details emerged.
Legal experts had said the fact that the couple have a child would be taken into account in a settlement - but so would the relative brevity of the marriage and the fact that most of McCartney's wealth was generated before he married Mills.
McCartney met Mills in 1999, the year after the death from breast cancer of his first wife, Linda. That marriage was one of rock's most enduring unions, and produced three children, including fashion designer Stella McCartney.
Mills and McCartney married at an Irish castle in June 2002, amid rumors the former Beatle's children disapproved of their new stepmother. The couple's daughter was born the following year.