Shevell ensured it was a family affair by wearing a long-sleeved, knee-length white dress designed by Stella McCartney, Paul’s fashion designer daughter.
The couple was showered with flower confetti by a small group of friends and family after the civil ceremony at Westminster Register Office.
The town hall was where McCartney married his first wife, Linda, in 1969. She died in 1998 after losing her battle with breast cancer.
The low-key ceremony, which was followed by a party at McCartney’s north London home, was a stark contrast with his lavish second wedding to former model Heather Mills in 2002, when 300 guests filled a castle in Ireland.
That marriage ended in an acrimonious divorce, which was finally agreed in 2008 after almost two years of wrangling when Mills received a settlement worth £24.3 million (then $48 million, 30.8 million euros).
McCartney, 69, and his 51-year-old bride have been dating for four years and announced their engagement in May.
As they emerged from the register office, McCartney held up his new wife’s hand to loud cheers from hundreds of well-wishers outside, before heading to his home in the upmarket district of St John’s Wood for the reception.
Asked at the house how he felt, the former Beatle, wearing a dark suit with a white shirt and pale blue tie, told reporters: “Terrific, thank you. I feel married. I feel absolutely wonderful.”
Among the select number of guests at the ceremony was Beatles drummer Ringo Starr, wearing a dark suit over a T-shirt and trainers, and his trademark tinted glasses. He gave a peace sign to the crowd before going inside.
One fan was overwhelmed, shrieking: “That was a Beatle! That was a Beatle!”
McCartney’s appearance sparked even more hysteria, with hundreds of people shouting his name, including a woman from New York who could not believe her luck at being on holiday in London at the same time as the marriage.
“I’m 55, and I’ve been a fan all this time. I’m thrilled!” said Regina Bellisari. “My sister went to the first Beatles tour in the US, but I was too young. She always rubbed it in my face, but now I can finally get her back.”
Guests including Rolling Stone Ronnie Wood and guitarist Jeff Beck were later spotted arriving for the marquee reception in McCartney’s garden, where they were treated to a three-course vegan meal.
McCartney had one child with Mills — a daughter, Beatrice, who was born in 2003 — and another four from his first marriage. Shevell also has a son, 19-year-old Arlen, from her first marriage to a US lawyer.
Despite the pressures of dating one of the world’s most famous musicians, Shevell has largely kept out of the spotlight, although she appeared at ease with the hordes of photographers at Sunday’s wedding, giving them a big grin.
Questioned about her relationship by the New York Observer ahead of the big day, she expressed surprise at the public interest.
“I’m over 50. I work. That’s it. I haven’t been social and I have a small group of girlfriends. There really isn’t much to talk about.”
McCartney’s wealth was estimated at £495 million by Britain’s Sunday Times Rich List earlier this year.
But Shevell also has a tidy fortune of her own. She is heir to her father’s trucking business, New England Motor Freight, where she is a vice president.
She holds a degree in business administration from Arizona State University where she majored in transportation, and has also sat on the board of the New York Metropolitan Transit Authority for 10 years.