EDF, which is 85 percent owned by the French state, also pledged to cut millions more in costs and sell off assets in a bid to reduce its huge pile of debt.
"EDF is a group that is already in debt -- increasingly in debt -- and it is vital that we bring this debt under control," chairman Jean-Bernard Levy said in an interview with the Figaro newspaper published late Friday.
After hours of talks, the board gave the green light to raising €4 billion ($4.5 billion) of capital through a "market operation" to be carried out by the beginning of next year.
Paris will inject €3 billion, though where it will get the cash is unclear, following a similar capital increase for Areva in January backed by the French state.
In exchange, EDF will redouble its debt-cutting efforts, targeting cost reductions of at least a billion euros in 2019 compared to 2015 -- well above original plans for €700 million of savings over three years.
The group also plans to raise €10 billion from selling off gas, coal and oil interests.
The measures are designed to help EDF better plan for the future, including paying for the maintenance of 58 French reactors and its takeover of the reactor arm of struggling nuclear giant Areva.
Unions, financial markets and even EDF's former finance chief -- who resigned in March -- have for months cast doubts on the company's ability to handle all its investments, particularly Hinkley Point.
France's Economy Minister Emmanuel Macron repeated his government's commitment Sunday to EDF's plans to build the plant in southwest England alongside China General Nuclear Power Corporation.
But questions have been raised about the financial viability of the £18 billion (€23.2 billion, $25.5 billion) project, which will use largely untested technology.