The pregnant royal was on top form as she walked the red carpet for a charity event, telling reporters: "I feel very excited."
When asked if she and her husband Prince Carl Philip had a name in mind, the former model, who doesn't know the sex of her baby, smiled and said: "We're keeping that to ourselves."
"I feel very excited," said Princess Sofia of Sweden
Sofia was attending a fundraiser for Project Playground, a charity she co-founded in 2010 with her friend. The organisation helps underprivileged children in South Africa.
The royal, 31, attended the event solo as her husband Carl Philip, 36, had to cancel his appearance last-minute.
Swedish Royal Court spokeswoman Margareta Thorgren explained: "The royal family always tries to be at the events they have booked, but sometimes it is not possible and this is one such occasion. It's flu season and he has a fever."
The former model is expected to give birth in April
At eight months pregnant, Sofia is showing little signs of slowing down. Her red-carpet outing came just days before she visited the Riddarholm Church in Stockholm, famed as the burial church of Swedish monarchs.
Sofia was photographed standing next to Karl XII's grave, proudly showing off her large baby bump. The princess' black belted coat highlighted her bump even further.
When asked about their baby's possible name, Sofia said: "We're keeping that to ourselves"
Earlier this month Sofia also joined other members of the Swedish royal family at a special Te Deum thanksgiving service to celebrate the birth of Prince Oscar – Crown Princess Victoria and Prince Daniel's second child and the current third-in-line to the throne.
The young prince, who was born on 2 March, is the newest member of the Swedish royal family but it won't be long before another prince or princess arrives. Sofia is due to give birth in April.