Kate Middleton is a knockout in Alexander McQueen on date night with William

It's date night for Duchess Kate and Prince William!

The Duke and Duchess of Cambridge stepped out on Monday night for a very glamorous evening at London's Palladium Theatre for the annual Royal Variety Performance. The yearly event is held in accordance with Queen Elizabeth's patronage the Royal Variety, which the royal family has supported King George V and Queen Marry first attended a performance in 1912. Last year, a newly pregnant Meghan Markle and Prince Harry attended on the queen's behalf, while the Cambridges had attended the year prior.

The parents-of-three opted for their black-tie best for the occasion, with Prince William looking dapper in a simple black tuxedo.

However, it was Kate's glamorous Alexander McQueen gown that truly stole the show. With its sheer lace and fitted bodice, the long-sleeved creation was a bolder look for the duchess, who normally opts for monochromatic styles and simple silhouettes. The duchess accessorized the look with Erdem earrings, and black stilettos and a black clutch, both believed to be by Jimmy Choo (you can shop the royal's heels here).

The fundraiser, which helps raise money to help hundreds of entertainers throughout the UK who are in need of aid, whether due to health issues or old age, was met with a variety of musical theater performances, including from the show "Marry Poppins" and "Come From Away."

"I love Mary Poppins!" the duke was overheard revealing while meeting the show's cast members before the performance.

For more on Will and Kate's date night, watch the video above.