Prince William, 28, and commoner Kate, 29, spent their last night as single with the Prince delighting people who had camped for days by shaking hands with them last night.
"All I`ve got to do is get the lines right", he quipped as he easily mixed with cheering crowds in The Mall.
Hundreds of thousands of people have converged on London from all over the world to attend the royal wedding.
The wedding ceremony in the ancient Westminster Abbey is scheduled for 11 GMT (0430 IST).
Thousands of street parties have been planned across Britain to celebrate the first wedding of Queen Elizabeth`s grand-children.
Since early morning, major television channels began their live coverage amidst largely clear skies and thousands of excited fans of the royal family.
It is estimated that the event will be watched by a global audience of nearly 2 billion people on television and online.
The Archbishop of Canterbury will conduct the wedding ceremony, which will include Kate vowing to "love, comfort, honour and keep" Prince William but not to `obey` him.
William spent last evening with the Prince of Wales, Duchess of Cornwall and Prince Harry, while Kate and her family gathered at the Goring Hotel, in Belgravia, a short distance from Westminster Abbey.
The weather office said the day will start off dry but cloudy in London but there was a risk of heavy showers developing later on.
The Scotland Yard said 5,000 officers will be on duty, with more than 900 along the wedding route.
Invitees to the wedding include royal families from various countries, political leaders and people of different walks of life, including an Indian-origin shopkeeper couple from Kate`s village of Buckleberry.
Prince William and Kate said in a warm message yesterday: "We are both so delighted that you are able to join us in celebrating what we hope will be one of the happiest days of our lives.
"The affection shown to us by so many people during our engagement has been incredibly moving, and has touched us both deeply."