Gilded invitations issued in the name of Queen Elizabeth II were mailed earlier in the week, and more than half the guests were drawn from the royal couple's family and friends, palace officials said.
Around 50 members of the British royal family were invited -- although the Duchess of York, Sarah Ferguson, was not among them -- in addition to 40 members of foreign royal families.
A further 80 guests will be drawn from Prince William's philanthropic commitments, which include homelessness charity Centrepoint and the Royal Marsden Hospital, where his late mother Princess Diana was also a patron.
The host of British and foreign dignitaries on the list reflects Prince William's position as second-in-line to the throne, and though it is not a state event, 200 members of government, parliament and the diplomatic corps, as well as 60 governors-general and prime ministers from Commonwealth countries were expected to attend.