Mr Biti is one of President Mugabe's most vocal critics
Zimbabwean opposition leader Morgan Tsvangirai has named Tendai Biti as his choice for finance minister in a unity government with Robert Mugabe.
Mr Biti is secretary general of the Movement for Democratic Change (MDC), Zimbabwe's main opposition party.
Last week a Zimbabwean judge dropped treason charges against Mr Biti over an alleged coup plot, citing lack of progress in the case against him.
The cabinet in the new coalition government will be sworn in on Friday.
Mr Biti's new position will be a key one, given the country's economic collapse.
It was once considered the breadbasket of southern Africa, but now suffers some 90% unemployment, while the government has stopped releasing inflation figures and recently said that foreign currency could be used as legal tender.
Truth and reconciliation
Under the terms of last September's power-sharing deal, Mr Tsvangirai was given the choice of finance minister.
KEY MDC APPOINTMENTS
Finance: Tendai Biti, lawyer and student leader
Home Affairs: Giles Mutsekwa, lawyer with a military background
Health: Henry Madzorera, trained doctor
Constitutional Affairs: Eric Matinenga, lawyer who defended Mr Tsvangirai on treason charges
Deputy Agriculture Minister: Roy Bennett, farmer, forced to flee Zimbabwe
Once in the job, Mr Biti would focus on creating economic stability and attracting foreign investment, said Mr Tsvangirai - who is himself set to become prime minister on Wednesday.
"This [finance] ministry's mandate is to create a stable economic environment for all Zimbabweans... and to establish Zimbabwe as a strong investment centre," Mr Tsvangirai told a news conference, according to Reuters news agency.
Mr Tsvangirai also demanded that political detainees in Zimbabwe's jails be released prior to his swearing in - though he did not say what he would do if they were not.
The MDC leader said there were plans to set up a truth and reconciliation commission to address the deadly violence during the 2008 elections.
Other key MDC appointments included lawyer Giles Mutsekwa to home affairs, the ministry which controls the police and is to be shared with Zanu-PF.
Mr Mutsekwa has been in and out of jail and has a military background.
Roy Bennett was imprisoned after pushing a minister in parliament
Eric Matinenga, as Mr Tsvangirai's choice for minister of constitutional affairs, will be expected oversee the writing of a new constitution within the next 18 months.
Zimbabwean journalist Brian Hungwe says a surprise appointment was Roy Bennett, who lost his farm during the violent land seizures, as deputy agriculture minister.
He fled Zimbabwe for South Africa in 2006, saying he feared for his life after being accused of involvement in a plot against Mr Mugabe.
Mr Bennett spent eight months in prison from October 2004 to June 2005 - a sentence imposed by other MPs after he pushed a government minister during a heated debate in parliament about Mr Mugabe's controversial land reform programme.
Henry Madzorera takes on health and will have the task of dealing with the cholera outbreak which has now infected nearly 66,000 people and killed more than 3,300 since August.
Mr Biti - a lawyer and founding member of the MDC - is one of Mr Mugabe's most trenchant and vocal critics, say observers.
Shortly after the treason charges were dropped against him, he renewed his commitment to "finish this job that we started of removing the dictatorship of Robert Mugabe".