George is smiling in another image as he puts his hand on his sister's stomach and stares at something beyond the picture frame and in another similar photograph he looks in a different direction.
A fourth picture, showing the prince looking down lovingly at his baby sister, was previewed earlier on the official Kensington Palace Twitter and Instagram accounts.
All the images show the royal siblings sitting down with Charlotte propped up in George's lap by a pillow.
The princess appears to be wearing a romper suit with a jumper, while her brother wears a white shirt with blue piping detail around the collar, cuffs and front, and matching blue socks and shorts with shoes.
George visited his sister the day she was born in the private maternity wing of St Mary's Hospital in Paddington.
In the photographs the toddler prince appears to be dressed in the same shorts, socks and shoes he wore on the day of the visit.
The fourth picture was previewed on social media as a thank you from Kensington Palace to the hundreds of thousands of new followers the accounts have attracted since the royal birth.
The baby princess was taken by her parents to their Norfolk home a few days after she was born and she will be christened at a nearby church on the Queen's Sandringham estate.
Charlotte will be baptised at St Mary Magdalene Church on Sunday July 5 at a private ceremony led by the Archbishop of Canterbury, Justin Welby.
- PA
