Brussels: Philippe ascended the throne of Belgium after the emotional abdication of his father Albert II on Sunday, vowing to strive for unity in a nation divided by language and tradition.
The new sovereign, who at 53 becomes the seventh "King of The Belgians", was sworn into office by the joint houses of parliament shortly after Albert, aged 79, stepped down citing age and failing health.
"I swear to abide by the constitution and laws of the Belgian people, to maintain national independence and the integrity of the land," Philippe, dressed in full military uniform, said in the country`s three languages -- French, Flemish and German.
"I begin my reign with the will to serve all Belgians," he said in a first speech as king that brought a standing ovation in the federal parliament.
As cannons boomed out a 101-gun royal salute, Philippe said "Belgium`s strength lies in giving meaning to our diversity."
"Let us all together show our country a new surge of enthusiasm."
Flanked by his popular wife Mathilde, the first Belgian-born queen, Philippe and their four young children were greeted with wild cries of "Long Live the King" by a sea of people massed outside the palace as they appeared on its balcony.
He was later to review troops and attend the annual National Day military parade.
Under sunny skies and a light summer breeze, flags fluttered across Brussels as the day of pageantry began with a thanksgiving mass in the cathedral marking the handover after Albert`s 20 years at the helm of the fragile nation.
At a solemn abdication ceremony in the royal palace`s grandly chandeliered throne room, Albert stressed the need for the country`s leaders "to work tirelessly in favour of Belgium`s cohesion".
His voice breaking with emotion, he then turned to his wife of 54 years, Queen Paola, to say: "As for the queen who constantly supported me in my task I would simply like to tell her `thank you.`
"A big kiss", he added as she shed a tear.