Chief Justice Godfrey Chidyausiku said Tuesday the July 31 elections were "free, fair and credible."
"Robert Gabriel Mugabe was duly elected president of the Republic of Zimbabwe and is hereby declared the winner of the said election," Chidyausiku said.
The declaration -- despite widespread allegations of vote rigging -- clears the way for 89-year-old Mugabe to hold his high-profile inauguration and embark on another five-year term.[break]
"The constitutional court has finally issued its decision. In doing so it has brought the whole electoral process to an end," Mugabe´s lawyer Terrence Hussein told journalists.
"It has brought stability. It has brought certainty. We can now all move on. I think we now know who our president is for the next five years."
Mugabe has ruled the country for 33 years since independence from Britain.
Mugabe´s swearing-in had been delayed after Morgan Tsvangirai challenged the election results in a petition to the constitutional court.
The opposition leader later retracted the case, claiming he would not get a fair shake from the court.
Mugabe´s inauguration promises to be more high profile than in previous years, a show of power, perhaps designed to confer legitimacy amid persistent allegations of electoral fraud.
The ceremony´s organisers said around 40 heads of state have been invited to the event, to be held in a 60,000-seater sports stadium on the outskirts of the capital.
Thousands of Mugabe´s supporters are expected to troop in from across the country.
Zimbabwe´s electoral commission declared Mugabe the winner with 61 percent of the ballot, against his main rival Tsvangirai´s 34 percent.
The elections were to end a shaky power-sharing government formed by Mugabe and Tsvangirai four years ago to avoid a tip into conflict following a bloody presidential run-off election.
Tsvangirai condemned the election as "a farce" and "a massive fraud" and demanded a forensic audit of the election results.
Among other complaints, Tsvangirai queried the unusually high number of voters who were turned away from urban areas which are considered strongholds of his party.
He also complained that suspected rural supporters of his party were ordered by Mugabe party youth to feign illiteracy and vote in the presence of police and electoral officers.
In a surprise U-turn Friday, Tsvangirai withdrew his petition saying he would not get a fair hearing.
He said the courts had frustrated his efforts for the release of election materials to use as evidence.
But the constitutional court went ahead and made a ruling on the case.
Tsvangirai´s Movement for Democratic Change (MDC) party said it had been denied justice.
"We have not been accorded justice," party spokesman Douglas Mwonzora told journalists. "We are in this situation because we could not have the materials to prosecute our case.
"We will continue to struggle for justice in this country to make sure the rule of law is retained in our justice system."
An electoral court judge on Tuesday called for the prosecution of Tsvangirai´s lawyers for claiming in the application that the judiciary was not independent of the executive or of Mugabe´s ZANU-PF.
"The applicant (Tsvangirai) had the occasion to launch a scathing attack on this court and the entire judiciary," said Justice Chinembiri Bhunu.
"While the applicant´s reprehensible conduct may be attributable to ignorance of the law, the same cannot be said of his lawyers."
"Time has now come to rein in errant legal practitioners bent on bringing this court´s integrity into disrepute," he said, referring the matter to the attorney-general.
Mugabe was declared winner in a presidential run-off election in 2008 after Tsvangirai pulled out of the race citing violence which left 200 of his supporters dead and thousands displaced.
Local observers have called the 2013 polls flawed and Western powers have raised serious doubts over the vote, but regional organisations the African Union and Southern African Development Community were less critical.
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