Speaking at the event in Tharparkar, Sharif said this marked the beginning of a new era marked by a spirit of cooperation and political maturity.
The project is a brainchild of the government of Sindh province, which is ruled by Zardari's Pakistan People's Party (PPP), and Engro Corporation under a USD 1.6 billion investment plan.
Sharif and Zardari are traditional rivals whose parties - the PML-N and PPP, respectively - have dominated the political scenario for the past two decades. They briefly joined hands in 2008 to form a coalition government but the alliance collapsed within six months.
Sharif said: "In 2008, we accepted the mandate of the PPP and last year they accepted our mandate. This is a new beginning in Pakistan politics. Parties might have different manifestoes but at the end of the day their aim is the same - to serve national interest and people."
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Zardari and other PPP leaders looked on and smiled.
The premier thanked Zardari, who became the PPP chief after the assassination of his wife, former prime minister Benazir Bhutto, for inviting him to inaugurate the project.
The coal power project was inaugurated after a study showed billions of tonnes of underlying reserves in Tharparkar district.
Besides mining, the project involves six coal-fired plants of 660 MW each - something that energy experts say should have been done long ago.
In the coming days, thousands of tonnes of sand will be moved and an open-pit coal mine will go to a depth of around 130 meters, officials said. The initial task of removing sand will be completed within the next six months, they said.