Police kept watch from the rooftops for a visit that brought the center of Belfast to a standstill.
Flipping pancakes is a tradition leading up to Lent, so they joined in and flipped pancakes for the crowd. Some 50 to 100 people gathered near City Hall to watch the couple.
This is the third trip in recent weeks for the prince and Middleton. The couple traveled to Wales and Scotland last month, all in advance of next month's nuptials.
A "Kate" versus "Catherine" debate has emerged in recent weeks because of William's switch in using it and because "Catherine" or the initial "C" is being imprinted on official wedding memorabilia and commemorative china.
During their visit to Northern Ireland, Middleton mentioned casually that she thinks of herself primarily as Kate.
"I'm still very much Kate," said Middleton, when a woman outside Belfast City Hall asked what name she preferred.
William and Middleton also toured Greenmount Agricultural College in Antrim outside of Belfast, where they were shown a herd of 30 prize Holstein dairy cows and taught how to rate cows.
William drew laughs by comparing the qualities judges look for in cows to a dating website then refereed a tug of war between agricultural students.
The Associated Press contributed to this story.