The sweet snaps show birthday boy Prince Charles smiling and blowing out a candle on a fruit-covered cake, as his proud parents look on.
The little prince looked adorable in an oatmeal Fair Isle knit and navy trousers as he was pictured walking through the family's garden at Fischbach Castle.
Princess Stephanie wore an orange top with white floral detailing and a matching knitted cardigan, with blue jeans. Her hair was styled in a pretty half updo, and she accessorised with statement earrings.
Her husband, Prince Guillaume, sported a blue open-collared shirt and navy jeans.
The newest addition to the Luxembourg royal family also featured in the new portraits.
Prince François was born on Monday 27 March at the Grand Duchess Charlotte Maternity Hospital.
The Grand Ducal Court shared the first photos of the royal tot three days after his birth, with an official announcement stating: "The Prince, who will bear the first names of François Henri Luis Marie Guillaume, weighs 3.575 (7lbs 8 oz) and measures 53cm. Princess Stephanie and the baby are doing well. The Heir Couple, as well as his brother, Charles, are eager to introduce you to Prince François."
For the new family photos, François was bundled up in a white ensemble, as he snuggled against his mother in a cream knitted blanket.
In another image, Charles grins as he sits on his father's shoulders and clutches a biscuit, as his mother looks up and beams at her eldest son.
Prince François is third in line to the Luxembourg throne after his big brother. Prince Guillaume has been heir since his father Grand Duke Henri's accession in 2000.
It's the latest celebration for the Luxembourg royals, following Princess Alexandra's two wedding celebrations.
Grand Duke Henri and Grand Duchess Maria Teresa's daughter tied the knot with Nicolas Bagory in a civil ceremony at the City of Luxembourg Town Hall on 22 April.
The bride wore separates by Belgian label, Natan, for her civil ceremony. And for the religious service on 29 April, she wowed in an Elie Saab, which featured a crisscrossed bodice and an A-line silhouette.
Alexandra also wore a diamond tiara from the family's collection for her nuptials in Bormes-les-Mimosas, France.
Guillaume and Stephanie were among the royal guests at the wedding, with Charles given a starring role in the bridal party as a page boy.
The royal toddler looked adorable in a white shirt with blue shorts and navy socks and shoes for his aunt's special day.
Guillaume donned a traditional morning suit, while Stephanie stunned in a glittering navy gown by Paule Ka.
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