Princess Leonor’s historic moment in the spotlight has finally arrived. On her milestone 18th birthday, the Spanish royal took part in a swearing-in ceremony before the Cortes Generales.

During the ceremony, the 18-year-old swore allegiance to the constitution, committing herself to the legal order as embodied in the Cortes.

The heir to the Spanish throne promised to “faithfully perform her functions, keep and ensure that the Constitution and the laws are kept, and respect the rights of citizens and the Autonomous Communities.”

Princess Leonor, who is currently undergoing military training in Zaragoza, will be supported on her big day by her parents King Felipe and Queen Letizia, as well as her youngest sister, Infanta Sofia, 16. Despite the media attention, the future queen appeared in high spirits as she stepped into the limelight surrounded by her loved ones.

During one particularly heartfelt moment, the young royal shared a warm embrace with her parents who tenderly kissed her on the cheek following her moment in the spotlight. 

For the special occasion, Princess Leonor looked elegant in a tailored white suit which she teamed with a pair of pointed block heels. She wore her blonde locks in a simple low ponytail and accentuated her features with fluttery mascara and a sweep of pink lipstick. 

As for accessories, the Spanish royal elevated her outfit with a pair of diamond drop earrings complete with glittering blue gems. 

Queen Letizia, 51, looked her usual polished self in a royal blue dress, whilst King Felipe cut a dapper figure in a smart black suit and a blue tie to match his wife’s colourful garment.

Sofia, meanwhile, turned heads in a striking floral cape dress crafted by Erdem which featured a whimsical bow around the neckline and a flattering black belt around the waist.

Following the ceremony, Princess Leonor and her family watched a spectacular military parade outside the Spanish Parliament. 

The 18-year-old looked on proudly wearing the medals of Congress and the Senate which were awarded to her in the Congress of Deputies. 

Later in the afternoon, the Spanish royals will hold a reception at the Royal Palace of Madrid, where Leonor will receive the prestigious necklace of the Order of Charles III.

The prestigious piece of jewellery, created by Carlos III in 1771, represents Princess Leonor’s readiness to one day become queen. King Felipe VI received the Collar of the Order of Charles III on his 18th birthday back in January 1986.

Juan Carlos I and Sofia will reportedly join the royals at a private family lunch after the ceremony.

If Leonor ascends to the throne as expected, she will be Spain’s first queen regnant since her fourth great-grandmother, Isabella II, who reigned from 1833 to 1868.

It’s been an incredibly busy period for the future queen of Spain. Back in August, Princess Leonor bid an emotional farewell to her parents as she kicked off her military training at the General Military Academy of Zaragoza.

She will spend the first year of her training at the General Military Academy in Zaragoza, followed by a year in the navy. She will complete her third and final year at the General Air Academy.

The princess is following in her father Felipe’s footsteps, who undertook his own military training, before obtaining a Law degree at the Autonomous University of Madrid. The future King later enrolled in a Master’s Degree Course in International Relations at the Edmund Walsh School of Foreign Service of Georgetown University (Washington, DC).

Princess Leonor’s youngest sister Sofia, meanwhile, flew to the UK in August to start the first year of a two-year International Baccalaureate study program at UWC Atlantic College in Wales.

Other royals who have attended UWC Atlantic College include King Willem-Alexander of The Netherlands and his middle daughter, Princess Alexia, as well as Princess Elisabeth of Belgium and Princess Raiyah of Jordan.