Fans were quick to praise the move.
“Omg, am crying now, this is so cool of Catherine to do for this little princess,” one wrote.
Another said: “I’m American, a Royal watcher since the late 70s and I think Catherine is off-the-charts incredible!”
“Oh how gorgeous, the Duchess kept her promise to Mila,” one fan said.
Another wrote: “They both look so beautiful in pink dresses. Mila is such a brave little girl!”
“Just when I think I could nit admire Catherine more….” one said.
More to follow