Kim Kardashian relaxed her diet for a day to enjoy a slice of pizza while out celebrating her and her ex-husband Kanye West’s eldest child North’s birthday.

The SKIMS founder – who is opening five SKIMS retail locations – whisked North and her friends off to the Big Apple for her daughter’s 11th birthday on her private jet.

She rented a party bus that made several stops throughout the day including at Joe’s New York Pizza in Greenwich Village.

Her photo was snapped eating a slice of cheese pizza while standing up.

The reality TV star, 43, bent the wider end of the pizza slice slightly as she raised it to her mouth.

Kim Kardashian relaxed her diet for a day to enjoy a slice of pizza while out celebrating her eldest child North West's birthday

The SKIMS founder, 43, whisked North and her friends off to the Big Apple for her daughter's 11th birthday on her private jet

For the festive outing, the mom-of-four wore a short-sleeved, light gray shirt with a fitted, dark gray tank top layered over it.

She added matching grey leggings and open-toed brown pumps to her casual and comfortable look that allowed her to keep up with a gaggle of 11 year olds.

Previously, the Keeping Up With the Kardashians star revealed her weird preference for pizza.

In the November 15 episode of The Kardashians on Hulu, she ordered a slice of pizza in New York City and then proceeded to take the cheese off of it.

‘Is it weird that I don’t like the cheese on pizza? I just like the bread,’ she asked while removing the topping from the crust.  Later she reached for another slice and took the cheese off again before eating it.

At North’s party, Kim appeared to eat the cheese.

The pizza place was just one stop on the birthday party bus. Kim also took North and her friends to Paint Me Bear, Serendipity 3 and to an indoor amusement park.

North and her friends all sported pink ‘I [heart] NY’ pajama bottoms as well as matching, black shirts that had, ‘North’s 11th birthday party’ printed on the front.

Kim was also joined by a few close pals of her own, including La La Anthony and media personality Kai Cenat during the birthday celebration.

She rented a party bus that made several stops throughout the day including at Joe's New York pizza place in Greenwich Village

Her photo was snapped eating a cheese slice while standing up

The reality TV star, 43, bent the wider end of the pizza slice slightly as she raised it to her mouth

Kim was also joined by a few close pals of her own, including La La Anthony

For the festive outing, the mom-of-four wore a short-sleeved, light gray shirt with a fitted, dark gray tank top layered over it. She added matching grey leggings and open-toed brown pumps to her look

Grandma Kris Jenner didn’t make the trip to New York City with North but she did wish her ‘spectacular’ granddaughter a happy 11th birthday on Instagram.

‘Happy birthday to my beautiful granddaughter, North!’ she wrote behind a photo of the Los Angeles native wearing a Simba costume from her recent The Lion King performance. ‘Watching you grow into the amazing, talented, creative young girl you are has been one of the greatest joys of my life,’ she penned.

‘Your confidence is inspiring and it always amazes me how much energy, excitement and love you put into everything you do!!’ she wrote.

‘Whether it’s your singing, dancing, writing, amazing music producing, your love for fashion, everything you do you put your all into it,’ she penned behind a snap of herself, the birthday girl and Kim.