The decision, taken by the jailed leader, Abdullah Ocalan , ended 30 years of armed conflict, thought to have killed around 45,000 people, most of them Kurds.
The announcement was designed to coincide with Kurdish new year, or 'Nowruz'  and came in a pre-written letter from Ocalan.
"Today I start a new process witnessed by millions of people," Ocalan was reported as saying by the Turkish daily newspaper, Hurriyet, adding, "The period of democratic rights, freedom and equality starts."
Ocalan told supporters that they must lay down their weapons and move out of Turkey, "we are shifting from armed struggle to democratic struggle", he said.
The decision to end armed conflict comes after months of secretive negations between the PKK and Turkey's intelligence agencies.
The ceasefire is part of what Ocalan called a roadmap for peace in Turkey , and will be the start of a movement for a permanent cessation of hostilities.It is thought the ceasefire will be part of a wider system of reform that will give greater recognition to those of Kurdish origin in the country.