Eugenie posted a photo to Instagram of baby August surrounded by daffodils, wearing bunny slippers, whale-patterned pants and a bonnet.
“I’m so excited to be August’s mum and as you can see I’m enjoying my first Mother’s Day,” she wrote.
The princess also posted a photo of herself as a baby being held by her mother Sarah Ferguson, Duchess of York.
“I’m also celebrating my beautiful Mumma with this picture of us from March 1990,” Eugenie said.
“You’ve taught me so much.”
Eugenie and husband Jack Brooksbank welcomed baby August on 9 February at London’s Portland Hospital.
His full name is August Philip Hawke Brooksbank. It’s believed August was chosen in reference to Queen Victoria’s consort Prince Albert, whose middle name was Augustus. Hawke is a Brooksbank family name.