French businessman Jean-Baptiste de Franssu is set to take over as head of the Vatican bank, succeeding German lawyer Ernst Von Freyberg, who has run the bank since February 2013.
Freyberg, who has said he is leaving for personal reasons, has introduced reforms to make the bank - officially known as the Institute for Works of Religion (IOR).
The outgoing head is seen as having made the bank more transparent and compliant with international norms against money laundering, and has closed many suspicious accounts.
The Vatican on Wednesday said it would separate its bank's investment business from its Church payments work to try to clean up the institution after years of scandal, and vowed to become a "model of financial transparency".
The Church also plans to increase scrutiny on one of the two sections of the Administration of the Patrimony of the Holy See (APSA) which has also been hit by recent scandals.
APSA runs Vatican properties, handles income and spending, prepares budgets and acts as a central accounting department and purchasing office, the Reuters news agency reported.
Australian Cardinal George Pell, head of the Vatican's recently formed Secretariat for the Economy, told a news conference that the move was necessary in order for his department to "exercise its responsibilities of economic control and vigilance" over all Vatican departments.
To underscore the importance the pope attaches to cleaning up the Vatican, he issued an official Latin decree called a "Motu Proprio," modifying a Vatican constitution to shift the responsibility for the APSA department to the Secretariat.
The decree said all had to obey his order "regardless of anything to the contrary".
'Model of transparency'
A new central Vatican Asset Management department will handle investments, leaving the bank to concentrate on its original aim and focus on payment services for religious orders, Vatican employees and charities, Pell said, changes that will be phased in over three years.
Pell said he wanted the entire Vatican to become "a model of financial transparency instead of cause for occasional scandal" and that all the changes had been approved by Pope Francis, noting that the cardinals who elected the pope in 2013 had given him a mandate to make the Vatican transparent and scandal-free.
"We are aiming at substantial transparency. There will be audits and these reports will be audited externally," Pell said.
Pell said that the IOR "is in a peaceful transition" and Freyberg had "cleared the decks" for a new phase in the bank's history.
On Wednesday, the Vatican bank said in a financial statement that it had blocked the accounts of more than 2,000 clients and ended some 3,000 "customer relationships" as part of a clean-up process that nearly wiped out its profit.
Last year's profits were also hit by extraordinary expenses related to the hiring of external professionals, such as the
Promontory Financial Group, to help in compliance and transparency issues and account closures, it said.