Hundreds of people have been visiting her home and the shrine where her 1986 revolution culminated, leaving yellow flowers and lighting candles.
Mrs Aquino's body will lie in state at the De La Salle Catholic school in Manila from Saturday evening to Monday morning.
She will be buried beside her husband at the Manila Memorial Park in a private ceremony on Wednesday, her son said.
"Our mother peacefully passed away at 0318 [1918 GMT Friday] of cardio-respiratory arrest," the son, Senator Benigno Aquino Jr, told the media.
Hundreds joined informal ceremonies in honour of Mrs Aquino in Manila
"She would have wanted us to thank each and every one of you for all the prayers and the continuous love and support," he said.
"It was her wish for all of us to pray for one another and for the country."
Mrs Aquino, who was known as Tita (Aunty) Cory, had been admitted to hospital about a month ago suffering from a loss of appetite related to her condition.
A series of daily masses were held to pray for Mrs Aquino's health, at least one of which was attended by her former political rivals, President Joseph "Erap" Estrada and former first lady Imelda Marcos.
Catapulted to the top
Mrs Aquino was catapulted into politics following the murder of her husband, the prominent Senator Benigno "Ninoy" Aquino, who had been preparing to run for president.
He had already spent seven years in prison following President Marcos's declaration of martial law, with his wife as his only contact with the outside world.
Arroyo: Aquino "helped lead our nation to a brighter day"
Mrs Aquino said of her husband's death: "What is more important is that he did not die in vain and that his sacrifice, certainly, awakened the Filipino people from their apathy and indifference."
After winning the presidential elections in 1986, she went on to run a country deeply divided after years of martial law and communist insurgency.
She battled several coup attempts against her rule, protected the country's fledgling democracy and freed political prisoners.
In recent years, she campaigned against former President Estrada, but then reconciled with him to join protests against incumbent President Gloria Arroyo over allegations of vote-rigging and corruption.
She was nominated for the Nobel Peace Prize in 1986 and later received several awards and citations for her work to promote democracy and human rights.
Tribute from president
The current president of the Philippines, Gloria Arroyo, announced 10 days of national mourning.
"Cory Aquino helped lead a revolution that restored democracy and the rule of law to our nation at a time of great peril," she said.
"Our nation will mourn her passing. History was thrust upon her when her noble husband was cut down in the prime of his life, as he fought for democracy and the rule of law.
"She picked up the standard from the fallen warrior Ninoy and helped lead our nation to a brighter day...
"Our hearts go out to the family in this hour of grief and sorrow."
The US President, Barack Obama, has also paid tribute to Mrs Aquino.
His press spokesman Robert Gibbs said she had played a crucial role in Philippines history.
"Her courage, determination and moral leadership are an inspiration to us all and exemplify the best in the Filipino nation," he said.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.