Estelle Silvia Ewa Mary was born at the Karolinska University Hospital in north Stockholm in the early hours of February 23rd, 2012. She weighed 3,280 grams and was 51 centimetres tall.
Announcing her birth at a press conference, Estelle's father, Prince Daniel, said his feelings were "all over the place".
Estelle's first birthday party on Saturday is a private affair, but the Royal Court has posted fresh photos online of the birthday girl wearing the same dress that her mother, Crown Princess Victoria, wore when she turned one.
Well-wishers were encouraged to post greetings to Estelle on the Royal Court's official website and Facebook page.
Those who want to send gifts were asked to instead consider donating to a foundation that Victoria and Daniel established at the time of their wedding in 2010.
While the Royal Court has chosen to keep the occasion of Estelle's birthday low-key, Swedish media are making a big splash. One tabloid published a book about the little princess' first year of life.
All around Sweden, bakeries have prepared special Estelle-inspired treats.
"All the bakeries that created a new cake or pastry at the time of Estelle's christening will likely sell them again today," predicted Martin Lundell, CEO of Sveriges bagare och konditorer, a Swedish bakers' trade organization.
Estelle is the Duchess of Östergötland, a province in south Sweden where a national Estelle pastry has been created.
Sixteen bakeries took part in a competition to create the official sweet.
The winning cake was a marzipan-wrapped sponge cake which has a chocolate base and is filled with carrot paste and rhubarb and elderflower-flavoured whipped cream.
Estelle's official birthday photos, which show the princess blowing out a birthday cake candle, laughing and cuddling with Victoria and Daniel, were taken at Haga Slott, the palace where the young royal family of three lives.
TT/The Local/nr Follow The Local on Twitter