Turkey's ruling Justice and Development Party (AKP) said on Monday that it will re-elect President Recep Tayyip Erdogan as Chairman after a break of some three years, state-run Anadolu Agency reported.
After Erdogan signed the document, Yildirim told the president he had come back "home", adding: "Welcome, you have honoured (us)".
Erdogan signed a membership form, confirming his re-admittance to the party which he left when he was directly elected Turkey's president in 2014, Mustafa Atas, AK Party vice chairman, announced.
The previous constitution of the country prohibited any party affiliation for the president, however under the recent constitutional changes the ban is lifted.
Aktay also reiterated that the party will hold a meeting Tuesday to renew Erdogan's membership.
By taking over the party, Erdogan would also be able to exert control over the rival personalities and different factions within the AKP. For example, Erdogan had the final say on the list of candidates running for parliamentary seats. "Political parties play an important part in the Turkish political system and a leader who controls a party holding a majority controls many things".
Erdogan had travelled to the ceremony from his palace in a convoy including at least two dozen black vehicles driving on closed roads and carried live by all television channels.
Erdogan was accompanied by his wife Emine and was sat next to the AKP chairman and Prime Minister Binali Yildirim.
The vote switches Turkey's system from a parliamentary one to a presidential system, abolishing the office of the prime minister while boosting the president's powers.