Princess Isabella of Denmark is set to make history, with the teenage royal confirming she will enlist in the military after completing high school.

The 18-year-old daughter of Australian-born Queen Mary and King Frederik X will begin her service in August, becoming the first female member of the Danish royal household to do so.

Her decision also places her among the first women to take part in Denmark’s expanded conscription program, which now aligns service requirements for both men and women.

A ‘master stroke’: Princess Isabella of Denmark cheeky and self-deprecating joke praised

Following in the footsteps of her older brother, 20-year-old Crown Prince Christian, the princess will undertake guard duty with the Guardhouse Regiment in Slagelse.

“The princess will be among the first to serve 11 months of military duty,” the Danish Royal Family said in an official statement.

“His Royal Highness the Crown Prince also served his military duty at the Gardehusarkasernen in Slagelse.”

According to Danish tabloid BT’s entertainment editor Fie West, the move sends a strong signal from the monarchy.

“Technically, Isabella did not have to do military service, but here the Royal House chooses to take the lead and set a good example,” West said.

“Isabella is becoming a kind of role model for conscription.”

Former soldier Sascha Stork also praised the decision, describing it as “absolutely fantastic” that the young royal will serve.

“She has some super cool and exciting months ahead of her,” Stork said.

“It will be tough, but she will be built up to be able to solve the challenges she encounters on her way.

“The princess will get to know herself better and realise how much strength she has. After the 11 months, she will stand proud and tall.”

While her long-term plans remain unclear, Isabella is expected to pursue further study alongside her military experience.

“Whether the military will be the princess’ future career path is probably too early to say, but she will most likely also take another form of education,” West said.

The announcement comes just months after the young royal sparked debate during an appearance at a Danish music festival.

Isabella drew attention after she was photographed wearing a T-shirt emblazoned with the phrase “I f***** him yesterday”, complete with an arrow pointing to the right- believed to be merchandise from Danish hip hop group Suspekt.

The outfit divided opinion, with Danish political commentator Jarl Cordua among those to criticise the choice.

“‘F****d him yesterday’. The rich are having a party because the second-oldest royal child let loose at a festival yesterday wearing a shirt with the aforementioned text,” he wrote next to a photo of Isabella on Facebook, translated by SkyNews.com.au.

“Not surprisingly, there are people who love that kind of thing. I’m also in favour of the royals letting loose a little. They always have. They should definitely be allowed to. BUT. There are limits.”

Others, however, welcomed the moment. Long-time royalist and Danish TV presenter Jim Lyngvild described the T-shirt as “brilliant” and “the best PR move for the Royal House in many years”.

“I expect a lot from her… I LOVE that our royal youngsters also have personality and courage – and don’t follow the neat pleated flow,” he wrote on Facebook.

“The time of the ladies in the hat is over, Princess Isabella is in.”