Under UEFA president Michel Platini's "Financial Fair Play" plan, clubs will not be able to spend more than they generate through revenues while cash injections from rich benefactors will be severely restricted.
Those who fail to comply could ultimately be barred from entering European competition.
"The new financial fair play regulations were finally approved unanimously," UEFA general secretary Gianni Infantino told reporters after an executive committee meeting.
"The main rule is the break-even requirement which will be phased in over the next three years.
"It is not as easy to swallow for everyone but everyone understands it is necessary.
"They are there not to punish clubs, they are there to help clubs. We don't want to kill anyone, this is why we have a phased-in approach."
"Clubs could spend an unlimited an amount of money on those things but when it comes to salaries and transfer fees they have to manage their cost structure in a much more prudent way," said Andrea Traverso, head of club licensing at UEFA.
"If clubs want to spend 50, 60 or 70 million (euros), why not, provided they have the money coming from their revenues, this will continue in the future," he said.
"The problem is when you don't have the money."
The European Clubs' Association (ECA) said it welcomed the plan.
"This is really a huge achievement," ECA president Karl-Heinz Rummenigge said in a statement. "The measures will shape
