Devastated Jack Schlossberg was spotted pushing his little nephew into sister Tatiana’s New York City apartment Tuesday — shortly after the family announced that she had died following a battle with terminal cancer.

Schlossberg, 32, who is running for Congress in the 12th Congressional District being vacated by Manhattan Rep. Jerold Nadler, looked disheveled and puffy-eyed as he hurried the stroller into his late sister’s luxury Park Avenue apartment building.

Tatiana, a married mother of two young children, tragically died on Tuesday at age 35 from leukemia.

Jack Schlossberg in a dark puffer coat, looking over his left shoulder.
Jack Schlossberg was spotted pushing a stroller into his late sister’s apartment building.Robert Miller for NY Post

“Our beautiful Tatiana passed away this morning,” the JFK Library Foundation announced on Instagram.

“She will always be in our hearts.”

Last month, Tatiana revealed in a tear-jerking New Yorker essay that she had less than a year to live after being diagnosed with myeloid leukemia with a rare mutation.

She was given the terminal prognosis in January — and wrote that her immediate family was helping her raise her two small children — Edwin, 3, and a 19-month-old daughter — as she underwent treatment.

Jack Schlossberg pushing a child in a stroller into an apartment.
Tatiana Schlossberg had two children, the youngest was 19 months old at the time of her death.Robert Miller for NY Post

Schlossberg previously boasted about being a devoted uncle, telling Today in 2022 that he prefers to call his nephew by his own name.

“His name is Edwin, but I like to call him Jack,” the Kennedy heir cheekly told the news outlet, eagerly telling anchor Savannah Guthrie that he visits the little tyke every chance he gets.

Man in a gray cap and coat walking into 888 Park Avenue.
A man seen carrying flowers into Tatiana’s Park Avenue building on Tuesday.Robert Miller for NY Post

“I can’t get away from him. I love him.”

Schlossberg’s sister Tatiana was diagnosed with Inversation 3, a rare mutation generally seen in older patients, and spent the past 18 months in treatment — receiving a bone-marrow transplant, chemotherapy, immunotherapy and blood transfusions.

Tatiana is the youngest granddaughter of President John F. Kennedy. She was diagnosed with cancer just hours after she had given birth to her second child in May 2024.

Prince William, Jack Kennedy Schlossberg, Tatiana Kennedy Schlossberg, and Caroline Kennedy.
Schlossberg was diagnosed with terminal cancer shortly after giving birth to her second child.AFP via Getty Images
Jack Schlossberg walking briskly on a sidewalk at night, carrying a red bag.
Jack Schlossberg is pictured walking briskly after leaving his late sister Tatiana Schlossberg’s Park Avenue apartment on Tuesday, December 30, 2025.Luiz C. Ribeiro for New York Post

In her article, she described the agonizing prospect of her children growing up without memories of her.

“My first thought was that my kids, whose faces live permanently on the inside of my eyelids, wouldn’t remember me. My son might have a few memories, but he’ll probably start confusing them with pictures he sees or stories he hears,” the daughter of Caroline Kennedy, 67, and Edwin Schlossberg, 80, wrote.

“I didn’t even really get to take care of my daughter – I couldn’t change her diaper or give her a bath or feed her.”

She leaves behind her husband, George Moran, their two kids, and her parents. She is also survived by her older sister Rose, 37, and younger brother Jack.