Minnelli, the Oscar-winning daughter of actress Judy Garland, said her vows before a packed house of stars that included Michael Jackson and Elizabeth Taylor.
Singer Roberta Flack said: "It was very emotional, very passionate."
"It didn't sound scripted - it didn't sound like somebody said: 'You know, Liza, you're a show- woman star. David you are a great entrepreneur. We want you to say this.'
"It was all from the heart. It was really beautiful."
Model Helena Christensen said the couple had exchanged rings and then "made beautiful speeches to each other".
They had also "kissed and kissed and kissed," she said.
Singer Dionne Warwick said: "When the minister said: 'I now pronounce you man and wife' - that was the best part."
English actress Sally Kirkland said the wedding had been "brilliant, joyous, delightful" and "romantic as hell".
Actress Joan Collins compared the wedding to her own, a month ago.
"The wedding was lovely - almost as beautiful as ours," she joked. " I wish them to be as happy as we are."
Minnelli's wedding - her fourth - came after she rebounded from health problems that threatened her career.
In a white dress by Bob Mackie, Minnelli, 56, showed little sign of the hardship she has endured in the last few years through back and hip surgery, viral encephalitis and a fight against an addiction to pain-killers.
Hundreds of people had lined Fifth Avenue to watch fleets of black limousines take guests to the city's Marble Collegiate Church.
Elizabeth Taylor and actress Marisa Berenson stood as maids of honor and Jackson and his brother, Tito, childhood friends of Gest's, were the best men.
The high-powered bridal party included actors Tony Franciosa and Robert Wagner, actresses Mia Farrow, Janet Leigh, and Gina Lollobrigida, and singers Petula Clark and Michael McDonald, former EastEnder Martine McCutcheon and singer Chaka Khan.
Guests also included Diana Ross, Patricia Neal, Luther Vandross, Lauren Bacall and Carol Channing.
"As long as he keeps trying, they will make it. Happiness is very elusive and we wish them the best of luck," said actor Mickey Rooney on the way in to the ceremony.
Unforgettable
Minnelli broke with tradition, arriving an hour before the ceremony, to change into her wedding dress. Taylor and best man Michael Jackson arrived 15 minutes after the wedding was due to begin, with Diana Ross.
McCutcheon was the first British arrival, wearing a floor-sweeping black gown, as instructed by the bride.
Star guests
Michael Jackson
Michael Douglas
Anthony Hopkins
Elizabeth Taylor
Joan Collins
Mia Farrow
Liam Neeson
Donny Osmond
Graham Norton
Andrew Lloyd-Webber
Queen guitarist Brian May, who wore a light grey suit, arrived with wife Anita Dobson, in a red and orange dress.
Minnelli and long-term bachelor Gest, who collects memorabilia of his new wife's mother, first met 15 years ago.
They were reunited at a comeback concert given by Michael Jackson last year.
The actress has attributed much of her success in battling health problems to Gest's support.
Minnelli was due to walk down the aisle to Unforgettable, sung by Natalie Cole.
Wedding rights deal
The guests queued to be searched by security guards and go through metal detectors before they entered the church.
Minnelli and Gest sold the rights to pictures from the wedding to OK! magazine and wanted to ensure unauthorised photographs were not published.
The wedding was followed by a reception at the Regent Hotel on Wall Street.
Liza's previous husbands
Entertainer Peter Allen (1967-72)
Producer Jack Haley Jr. (1974-79)
Stage
manager/ sculptor Mark Gero (1979-92)
Rocking to a 60-piece orchestra, entertainers performing there included Paula Abdul, Ed Ames, Tony Bennett, Roberta Flack, Gloria Gaynor, Robert Goulet, the Pointer Sisters, Shaggy and Dionne Warwick.
Invited guests not to show up included Elton John, Michael Douglas and Liam Neeson.
The wedding list was from top New York shops including Tiffany, the jewellers, and included 12 silver platters at a total of $24,350.
The couple plan to honeymoon in Thailand before Minnelli begins a European tour.