Thousands of people are expected to line the streets of central London to watch floats, carriages, performers - and Jessica Ennis - in the Lord Mayor's Show.
The annual parade marks the inauguration of the 685th Lord Mayor of the City of London, Alderman Roger Gifford, who will be carried through the capital in a golden coach.
Joining him will be Olympic gold medallist Ennis who will have the pleasure of using a Jaguar F-Type sports car.
The car will take the athlete along the three-and-a-half mile route, which passes around Bank and Aldwych.
Before the parade starts, Mr Gifford will arrive in the City on the royal barge Gloriana as it makes its third official outing this year following the Jubilee pageant and Olympic torch relay.
This year's show will showcase the talents of 6,500 people, 18 vintage cars, a tank and a steamroller among others.
It is expected to attract crowds of around half a million people, and will be broadcast live by the BBC.
In a split from tradition, there will be no after-show fireworks this year, with organisers believing 2012 has brought with it enough fireworks.
They said: "After the wonderful Diamond Jubilee and Olympic celebrations this summer, it was felt that there are only so many fireworks we should be sending up in one year. It has been agreed that the display will not take place this year."
Mr Gifford was elected as the 685th Lord Mayor of London in October and hopes all onlookers have a "splendid" day.