"As president, we will be in a position to effect the necessary changes," he said. "With the backing of the people, I don't think anything is impossible."
The Philippine Congress proclaimed Aquino as the nation's 15th president, formalizing the landslide victory of the son of revered democracy icons — Benigno Aquino Jr. and former President Corazon Aquino — in last month's first national automated elections.
The official congressional count, which ended Tuesday, showed Aquino defeating his eight rivals with more than 15 million votes — about 5.7 million ahead of his closest opponent, ousted leader Joseph Estrada.
Aquino, a quiet legislator who served nine years as a congressman and three years as senator, will take his oath on June 30.
He will inherit a nation grappling with poverty and debilitated by decades-long Marxist and Muslim insurgencies, military unrest, corruption, violent crime and political strife.
Aquino told reporters he felt "a little anxious, a little eager to start solving the problems that are still besetting our countrymen," and promised justice and "closure on so many issues."
Aquino will succeed Gloria Macapagal Arroyo, whose nine-year presidency was wracked by four coup attempts by mutinous troops and by opposition impeachment bids over alleged election fraud, corruption and human rights abuses.
There was no immediate comment from Arroyo, who is visiting China.
Her spokesman, Ricardo Saludo, called on Filipinos to rally behind Aquino and said the election "demonstrates that our democracy is vibrant, and our new electoral system is working for our people." In a statement, he pledged there would be a "smooth and orderly" transition to the new administration.
Aquino has said he will form a commission to investigate allegations of corruption and other wrongdoing during Arroyo's administration. Arroyo has denied all accusations.
In a move to show he is in command, Aquino said he plans to dismiss military chief of staff Gen. Delfin Bangit — who is close to Arroyo and had announced he would not step down when the new president takes office — but would likely retain the national police chief, Jesus Verzosa, who had offered his courtesy resignation.
Military spokesman Lt. Col. Arnulfo Burgos said Bangit would obey orders "as a professional soldier."
Aquino, a 50-year-old bachelor, campaigned largely on his family name and promised to follow the legacy of his parents, who are regarded as heroes in the country's struggle against the dictatorship of Ferdinand Marcos.
It was only after his mother died of cancer last August that he decided to run, spurred by a massive outpouring of national grief for the leader who helped end Marcos' 20-year rule in 1986.
Corazon Aquino inherited the mantle of her husband, an opposition senator gunned down by soldiers at Manila's airport in 1983 upon his return from US exile to challenge Marcos.
Estrada's running mate, Jejomar Binay, the mayor of Manila's financial district, Makati, will become vice president after defeating Aquino's candidate, Manuel Roxas II, in the separate race for the No. 2 position.
The new president is expected to get cooperation from Binay, who was a staunch supporter of Aquino's mother and led soldiers and police in defending her against a coup attempt by rightist military officers.
Aquino received congratulatory messages and pledges of cooperation from British Prime Minister David Cameron, Canadian Prime Minister Stephen Harper and Japanese Foreign Minister Katsuya Okada.
US Ambassador Harry K. Thomas Jr. said he was looking forward to working with the new Philippine government "to advance our common goals."
