The tall, 46-year-old former Olympic yachtsman will take the crown as the nation struggles with a towering 26-per cent jobless rate and as the northeastern region of Catalonia fights for the right to hold an independence referendum in November.
"In difficult periods such as these we are going through, experience in history shows us that only by uniting our desires, putting the common good ahead of individual interests and promoting the initiative, curiosity and creativity of each person, can we manage to advance to better scenarios," Felipe said.
Felipe, wearing a navy-blue suit, stressed his country's 1,000-year history of unity and diversity as he appeared with his elegant wife Letizia, dressed in a pink jacket, at a cultural award-giving ceremony in northern Spain's Monastery of Leyre.
It was the royal couple's first joint appearance in public since the 76-year-old King Juan Carlos announced on Monday he would abdicate to pass the crown to "a younger generation".
But the prince promised to devote all his strength to serving the Spanish people and "our dear Spain - a nation, a united and diverse social and political community that has its roots in a millennium-long history.