The Queen made Prince William the Baron Carrickfergus ahead of the ceremony on Friday morning.
The barony of County Antrim's oldest town has been extinct since 1883.
Following their exchange of vows, the couple's main titles are the Duke and Duchess of Cambridge.
Thousands of people have greeted the happy couple as they passed through London on a horse-drawn carriage following their marriage.
Prince William, who is colonel of the Irish Guards, wore the regiment's red tunic during the ceremony.
Representing Northern Ireland at the service were the First Minister Peter Robinson and the assembly speaker William Hay.
Carrickfergus is on the north shore of Belfast Lough, about 10 miles from Belfast. Carrickfergus Castle dates from about 1180 and is one of the best preserved castles in Ireland.
The mayor of the town said he was delighted the prince had been given the title and that he hoped he would visit in the near future.
People across Northern Ireland are decorating their houses and streets with bunting and holding street parties to mark the occasion.
Hundreds of people are attending festivities in a number of towns and villages, including Belfast, Londonderry, Newtownards, and Templepatrick.
A number of well-wishers gathered in St Columb's Cathedral in Londonderry to watch the ceremony on a big screen.A crowd of well-wishers gathered in the Fountain estate in Londonderry
Londonderry woman Maisie Crawford has decked out her home with union flags.
"Diana would be so proud of William today," she said.
"He's a great young man marrying a beautiful young girl."
Jacqueline Dorrian from Carrickfergus said she had decided to arrange a party a fortnight ago as a way to bring neighbours together.
"I went round the doors first to see who was interested and everybody said they were," she said.
"Everybody chipped in and everybody's come out to put up the bunting and do the face painting for the kids.
"It's good for the community and the whole area to get everyone together on a day like this."
Part of the bride's dress was hand-made by the Royal School of Needlework using the Carrickmacross lace-making technique, which originated in County Monaghan in the 1820s.
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