Abdullah Öcalan, now 75 years old, who, in addition to being a leader, helped found the movement in 1978, has been held in isolation on a prison island outside Istanbul since 1999.
It was from there that he issued a statement about dissolving the PKK, and thus ending the decades-long conflict with Turkey that has cost tens of thousands of lives.
Members of the pro-Kurdish party DEM read out the statement from Öcalan, after visiting him in prison:
"All armed groups must lay down their weapons and the PKK must dissolve itself."
Questions about exchange
There is still a great deal of uncertainty about what the statement will entail, according to Aras Lindh, an analyst at the Total Defense Research Institute, FOI.
His statement was quite short and contains nothing about what the PKK would get in exchange for laying down their weapons. That is a question that needs to be answered, but we don't have that information today, he says.
It was last autumn that the leader of the far-right party MHP, Devlet Bahçeli, who is closely allied with President Recep Tayyip Erdogan, extended a hand and offered Öcalan the opportunity to visit the country's parliament to "renounce terrorism" and dissolve the PKK.
Shortly after, Öcalan was given the opportunity to meet with relatives for the first time in several years, in what was described as an attempt by the Turkish government to calm the situation in the Kurdish border areas with Syria.
Öcalan then let it be known that he was "ready to take necessary measures".
Shifted power balance
Turkey's attempt to resume dialogue came only a few weeks before Syrian rebels overthrew Syria's dictator Bashar al-Assad, which shifted the regional power balance and put Turkey's complex relationship with the Kurds in a new spotlight.
Since Öcalan was imprisoned in 1999, there have been several attempts to bring an end to the bloodshed that broke out in 1984. The latest attempt failed in 2015.
How will Thursday's message be received by supporters?
Öcalan is a central figure among PKK supporters, even though he has been in prison for 26 years. But against the backdrop of the many questions that still hang in the air, the immediate response may still be cautious, says Aras Lindh.
The question is how other influential people within the PKK view the message in Öcalan's statement. We'll just have to wait and see the reactions.
The Kurdistan Workers' Party (PKK) was founded in 1978 as a Marxist party.
The movement's goal was a Kurdish state in southeastern Turkey and adjacent parts of neighboring countries.
In 1984, the PKK took up arms against the Turkish state in the fight for independence.
The PKK is listed as a terrorist organization by Turkey, the EU, and the USA.
Turkey has, among other things, demanded tougher action against the PKK in Sweden in order to approve Sweden's NATO membership.
