He said he hoped to return the nation to the world community after years of isolation.
"We are going to be new brooms" for change, he told about 500 party leaders and activists at a party conference to finalise a platform. He will be pitted against long-time ruler President Robert Mugabe (89) in elections.
No date has been set but it is expected to be held around September.
Tsvangirai described his Movement for Democratic Change party as the main champion of a new, reformed constitution accepted by 95% of the vote in a March referendum. "We have a new Constitution, we must definitely have a new government" to open Zimbabwe for business and restore human rights and the rule of law, he said.
The conference, which went into closed session after Tsvangirai's speech, ends on Sunday with the release of an election manifesto.
Leaks to local media organisations of its proposals suggest the MDC intends to cut spending on the military, traditionally dominated by Mugabe's Zanu-PF party loyalists, and offer retirement to long-standing military and police commanders. The proposal is fraught with peril since commanders of the security forces are Mugabe loyalists and some have been disrespectful toward Tsvangirai.
It also calls for a full overhaul of chaotic voters' lists and electoral laws the party says have led to vote rigging in the past.
Tsvangirai said a return to stability will create jobs in the battered economy that faces record unemployment since a meltdown triggered by the often-violent seizures of thousands of white-owned commercial farms which began in 2000, collapsing the agriculture-based economy.
Reforms within the police and military are demanded in the coalition agreement between Tsvangirai and Mugabe forged by regional leaders after violent and disputed elections in 2008 but Mugabe has dismissed calls for such reforms.
Senior generals have repeatedly vowed their allegiance to Mugabe and have refused to salute Tsvangirai since he became prime minister in 2009, arguing he did not take part in the guerrilla war that ended colonial rule in 1980 and brought Mugabe to power.
The independent legal and constitutional research group Veritas said in a report on Friday that among reforms that have not been tackled as called for by the coalition agreement are ones on freeing up the media, including the sole broadcaster controlled by Mugabe, and the repeal of security laws stifling free expression and freedom of association.
Regional mediators are insisting that more progress be made on these reforms before elections are held. The chief mediator on Zimbabwe, President Jacob Zuma, is expected to make a state visit to Zimbabwe sometime in the next few weeks. – Sapa-AP