Emmerson Mnangagwa has vowed a “brighter tomorrow” for Zimbabwe after being sworn-in as president.
He also announced an inquiry into the deaths of six people in clashes between the army and opposition supporters after the July vote. The violence was “unacceptable”, he said.
The opposition MDC Alliance continues to reject the result despite a court ruling on Friday upholding it.
July’s poll was the first since veteran leader Robert Mugabe was ousted.
MDC leader Nelson Chamisa says he was robbed of victory and did not attend Mr Mnangagwa’s inauguration.
What did Mnangagwa say?
He again condemned the post-election violence, saying it “should be alien to our nature as Zimbabweans” and offering condolences to the victims’ families.
Describing himself as a “listening president”, he said his government was committed to constitutionalism, the rule of law and judicial independence.
“The Zimbabwe we want is a shared one and transcends party lines,” he said.
Mr Mnangagwa – who from the Zanu-PF party of Mr Mugabe – also vowed radical economic reforms aimed at attracting foreign and domestic investment.
“The creation of jobs, jobs and more jobs will be at the core of our policies,” he said.
Relishing the moment
By Shingai Nyoka, BBC News, Harare
Thousands of supporters in bright Zanu-PF party regalia stood in line for hours before the ceremony.
It was a festive affair with top flight artists performing onstage as they waited for Mr Mnangagwa to arrive.
Outside dozens of vendors roasted meat and sold food. Big Businesses posted billboards congratulating Mr Mnangagwa.
Regional heads of state past and present attended, the endorsement that president-elect Mnangagwa was looking for.
Security has been tighter than usual around the stadium, with rigorous checks.
The main opposition was not represented. But Mr Mnangagwa’s supporters don’t seem to care. This is their moment and they want to relish it.
How do others see the vote?
After the court upheld the election result Mr Chamisa insisted that he had a “legitimate claim” to lead the country and vowed to lead peaceful protests.
Hours before Mr Mnangagwa’s inauguration, the US International Republican Institute and National Democratic Institute said Zimbabwe’s system did not allow political parties to be treated equally and citizens to vote freely.
They urged all sides to avoid “acts or threats of retribution against political rivals following the Constitutional Court’s decision”.
The US has maintained some sanctions on senior Zanu-PF officials including Mr Mnangagwa. The EU has removed most of its sanctions.
EU election observers said after the Constitutional Court ruling that all parties should accept the verdict but also suggesting that President Mnangagwa had benefited from an “un-level playing field”.