Kate, who was dressed in a grey coat designed by Tory Burch, and William were introduced to the singer and rapper during the second half of a basketball game between the Brooklyn Jets and the Cleveland Cavaliers.
After the royal couple had chatted briefly with the music stars, they returned to their seats next to basketball legend Dikembe Mutombo. Beyoncé and Jay Z were placed in seats directly opposite.
The duke and duchess were later taken backstage to meet the players including the Cavaliers' LeBron James, aka 'King James'. And yes, the family were treated to their very own basketball shirts emblazoned with 'George 1' and 'Cambridge 7.'
The royal couple's visit to the Barclays Centre marks a partnership between the National Basketball Association and their Royal Foundation.
The Express reports William and Kate also went to a dinner in the boardroom to celebrate to collaboration between the foundation's United for Wildlife and Coach Core programmes and the NBA's global social responsibility initiative.
Speaking to 'King James' after the game, William said how much he enjoyed his first basketball match.
"It was good, really good. Our first time," the prince told the 6ft 8in star. "I went to the White House for the first time," William added. "It was quite daunting."
Tuesday is another busy day for the royals - they are expected to visit the National September 11 Memorial Museum and the Memorial Reflection Pools before attending the University of St. Andrews 600th Anniversary Dinner at the Metropolitan Museum of Art.
They will fly back to the UK on Tuesday immediately after their final engagement.
Catch up on day two of the couple's tour of the east coast below: