Sarah Benioff, chief executive of the Community Development Foundation, a public body funded by the Department of Communities and Local Government, will become deputy director of the office's participation team.
Pat Samuel, head of the Treasury's charity and third sector finance unit, has been appointed deputy director of the partnerships team.
The infrastructure deputy directorship will be taken on by Helen Stephenson, head of strategic policy and partnerships at the Big Lottery Fund.
Hilary Norman, deputy director of social enterprise at the Cabinet Office, will head a new team combining social enterprise and finance.
The office will re-advertise for a deputy director to preside over communications and strategy.