Mary Jean Lacaba, who had been held since January 15 along with an Italian and a Swiss national, has said their Abu Sayyaf captors did not mistreat her, according to the vice governor of Jolo island where they were seized.
The vice governor, Nur-Ana Sahidulla, said the militants freed Lacaba into her care as a sign of good faith and to prove they were not after a ransom.
Sahidulla said she also saw the two other Red Cross aid workers –Eugenio Vagni, 62, of Italy and Switzerland's Andreas Notter, 38 – and they appeared "okay."
She said Lacaba, 37, was to have been beheaded under a deadline set by the kidnappers but "due to our appeals, they apparently changed their minds."
Lacaba was flown from Jolo island to the port city of Zamboanga, where she was reunited in private with her husband before boarding a chartered plane to Manila.
As she walked to her plane, a haggard but smiling Lacaba waved to reporters at the Zamboanga air base.
Interior Secretary Ronaldo Puno said Lacaba was too tired to give details about her captivity but had indicated the two other hostages were "still safe, in good condition and their health is holding up,"
The International Committee of the Red Cross welcomed her release, saying she "appears to be in good health, although very tired and extremely worried for her two colleagues... who are still being held hostage."
Sahidulla said the militants would only negotiate for the release of Vagni and Notter once the military had withdrawn from the town of Indanan, a Muslim rebel stronghold on Jolo.
Puno said they could pull back government forces a little way to enable any release, but would not withdraw the troops.
The Abu Sayyaf had previously demanded that all military and police forces be withdrawn from most of Jolo by March 31 or they would behead one of their hostages.
The military withdraw partially from five towns but refused to go further, saying that would leave the island vulnerable to Abu Sayyaf attacks.
President Gloria Arroyo voiced her relief at Lacaba's release, saying that it was proof that "we should always stand behind our policy of dealing firmly with any form of lawless behavior."
Efforts to isolate the kidnappers were continuing, Puno said, adding that about half of the kidnapping gang had since abandoned the group, leaving about 50 men.
A landmine exploded Friday under a military truck transporting soldiers to the security cordon near Indanan, injuring three soldiers, regional military chief Lieutenant General Nelson Allaga said.
Abu Sayyaf militants have kidnapped several other westerners over the past decade, many of whom, according to the Philippines military, were ransomed off for millions of dollars.
They also murdered an American hostage, Guillermo Sobero, in 2001, while a second American, Christian missionary Martin Burnham, was killed in a military attack the following year that led to the rescue of his wife Gracia.