Phillips, 30, who is 13th in line to the throne but does not use a royal title, and Tindall, 32, were scheduled to be wed at Edinburgh's Canongate Kirk in a private ceremony attended by the queen, William, his bride Kate Middleton and a host of other royals and sporting stars.
The couple, who largely shun the limelight, won't have their ceremony carried on live television and crowds gathering in the Scottish city ahead of the service were told by police there would be little to see.
Phillips is known better for her sporting achievements than royal heritage, and is a world class equestrian who is likely to compete in the 2012 Olympics. Her longtime partner Tindall is a leading rugby player who has captained England in international matches.
Dressed in their trademark style, casually in jeans, the couple greeted well wishers late on Friday as they appeared at Canongate Kirk for a final rehearsal.
But the prospect of even a brief glimpse of the royal family on Saturday was enough to entice hundreds of people onto the streets of central Edinburgh, including a few dozen who camped overnight to win a front row view.
Waving a Canadian flag, Margaret Kittle, 76, said she had traveled from Ontario, Canada, and staked out a spot on Friday night. "I flew over last Saturday and have been here since last night. I started following the royals after I saw George VI and the Queen back home in Canada when I was four-years-old," she said.
Helen Sutherland, a 65-year-old from Muir of-Ord in the Scottish Highlands, was wrapped in a warm blanket as she waited for a glimpse of Britain's newest royal couple. "It got chilly through the night but we want to see the bride and her dress. They seem to be a very happy couple," she said.
After Kate's much admired demure lace wedding gown - designed by Sarah Burton of the Alexander McQueen fashion house - experts predicted Phillips would opt for a more daring style.
Phillips, who once sported a tongue stud, is known for her sometimes revealing outfits. "She pushes her style as far as she can and knows where to draw the line. She knows the rules and might bend them a little," said Peta Hunt, fashion director at You and Your Wedding magazine.
William and Kate - now known as the Duke and Duchess of Cambridge - joined a glitzy cocktail party with couple and other royal relatives late Friday aboard the former royal yacht Britannia, hired out for the occasion.
But the party was a rare moment of public glamor for the usually publicity-shy Phillips, who will celebrate with a private wedding reception at the Palace of Holyroodhouse, the queen's official home in Scotland.
The couple are known for putting their devotion to sport ahead of their celebrity, and plan to postpone their honeymoon as both are due to feature in major events next week - the bride in horse trials, and the groom in England's rugby international against Wales. Phillips also plans to continue to use her maiden name when she competes.