Just like her late mother-in-law did years ago, Kate on Wednesday visited Great Ormond Street Hospital, which has long been supported by the royal family.
In the hospital, Kate, 36, who is due with her third child in April, comforted several children at their bedsides.
She also sat and talked with children as they completed an art activity in the hospital's playroom.
While talking with patients and staff, Kate revealed that pasta with olives is a favorite food of Charlotte, 2.
Eagle eye royal enthusiasts noticed Kate was wearing only her gold wedding band at today's hospital visit, leaving at home her sapphire and diamond engagement ring that once belonged to Diana. Kate, mindful of her interactions with patients, followed hospital recommendations and wore minimal jewelry.
Kate later joined some of the hospital's young patients on stage as they unveiled a new building with additional facilities to allow parents to spend the night with their children.
"It's been my first visit to Great Ormond Street and I've been so impressed by everything I've seen and the scale of the work going on here," Kate said in a short speech. "It's been wonderful to meet so many families and young people.
"I've been so inspired by their bravery and courage at such a difficult time," she said.
The hospital was one of the six charities Diana focused on until she died in a car crash in Paris in 1997. After Diana's death, a hospital spokesman said her support had been “invaluable and incalculable" and the hospital set up a memorial fund in her name.
In her remarks, Kate also thanked hospital workers for their work improving the facilities.
"My main message is congratulations to you all," she said. "It means so much to the families, both to the parents and children. You can see the real family element the hospital brings at such a difficult time."
In the afternoon, Kate changed from the brightly-colored coat she wore at the hospital into athletic gear for a visit to a primary school in Mitcham in southwest London.
"I was really sporty when I was little," Kate said. "Less so now that I've got lots of babies."