The Princess, who is expecting her second baby this summer, took to the social media site in honour of Mother's Day.
She uploaded an image of herself and her little boy holding hands as they walked through a light dusting of snow. Eugenie captioned the sweet snapshot with a heartfelt message. See the pregnant Princess enjoy a recent outdoor visit in the clip below...
WATCH: Pregnant Princess Eugenie visits Horatio's Garden
She wrote: "I love being your Mumma! Happy Mothers Day! Xx," and royal watchers were quick to respond.
One commented: "Happy Mother's Day… beautiful pic and August Philip is so adorable," while others added: "God bless you and your family," and: "Fantastic picture and caption".
The news that Eugenie and her husband Jack Brooksbank were expecting their second child was announced by Buckingham Palace in January, with a statement reading, in part: "The family are delighted and August is very much looking forward to being a big brother".
Princess Eugenie shared the lovely new picture on Instagram
Eugenie also took to her personal Instagram account to share the exciting news alongside an adorable photo that showed August kissing her growing bump.
"We're so excited to share that there will be a new addition to our family this summer," she wrote as Sarah, Duchess of York shared her joy at becoming a grandmother for a third time.
Eugenie with August and Jack at the Queen's Jubilee
She wrote: "I'm so proud of my girls and the beautiful women and mothers they have grown up to be. "I feel extremely blessed to call them mine. My darlings, you are my sunshine always & forever. #happymothersday."
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