It appears Meghan Markle’s famous friends spared no expense for her luxurious baby shower.

On Wednesday, Serena Williams and Amal Clooney will co-host the afternoon event for the pregnant Duchess of Sussex inside the grand penthouse of The Mark Hotel on the Upper East Side, according to the New York Post.

Described as the largest penthouse in the United States with more than 10,000 square feet, the two-floor suite, which is said to go for $75,000 ($A105,000) per night, boasts five bedrooms, six bathrooms, and four fireplaces, in addition to views of Central Park and the Metropolitan Museum of Art.

It is said to be America’s most expensive hotel room. Williams is reportedly covering the tab.

With Clooney, 41, and Williams, 37, at the helm, the guest list is also said to include Markle’s BFF, stylist and Good Morning America contributor Jessica Mulroney, as well as designer pal Misha Nonoo, hairstylist Serge Normant and former Suits co-star Abigail Spencer.

Shower activities will reportedly include a lesson in flower arranging with a dessert spread from chef Jean-Georges Vongerichten.

The Sun also spotted countless designer suitcases, a fairy floss machine, and a baby’s crib valued at $400 being wheeled into the hotel.

As for the guest of honour, Markle, 37, is expected to depart New York on Wednesday evening, as she is set to join husband Prince Harry on their official three-day tour of Morocco.

The parents-to-be are slated to leave London on Saturday.

They are expecting their first child in April.