Zardari spoke to thousands of his supporters in the Pakistan People's Party (PPP) in the eastern city of Lahore to formally resume political activities, Xinhua reported.
Lahore is the stronghold of his political rival, Prime Minister Nawaz Sharif of the Pakistan Muslim League (PML-N).
In his first speech after leaving the presidency, Zardari told Sharif that he would support government efforts in achieving reconciliation in the country and in the fight against terrorism and violence.
"I will fully participate in the politics of the country and will remain in contact with the masses," the former president told his party members in Islamabad.
Zardari was barred from active politics when he was the president of the country but is free to now do so.
The day before he stepped down, Zardari said that he would not seek to become the prime minister but would remain focused in strengthening the PPP, which is now the minority party.
The PPP suffered a crushing defeat in three of the country's four provinces in the general elections in May this year and the party leaders said lack of leadership was one of the reasons for the
The PPP succeeded in forming a government only in southern Sindh province, which is considered as the only stronghold of the party.
Zardari had been the co-chairman of the PPP since the assassination of his spouse, Benazir Bhutto, in 2007 and his son, Bilawal Bhutto, assumed the leadership of the party.
However, Zardari was the man who actually ran the party during the five-year rule of the PPP since Bilawal was studying in Oxford and could not play an active role due to security threats to his life.
Although Bilawal remains chairman of the PPP as a symbol of the Bhutto clan, he will just be a figurehead because his father would attend to the day-to-day affairs of the party.
In a luncheon he hosted for Zardari last week, Prime Minister Sharif praised the former president for stepping down peacefully and in promising to cooperate with the government.
Zardari was elected president in 2008 after then military president Pervez Musharraf resigned after fearing a parliamentary impeachment.
--IANS (Posted on 09-09-2013)