Ed Miliband warned that every chief executive in the UK should brace themselves as his party seeks a "fairer deal" for workers.
The new Labour leader said that the UK was too dependent on the financial services industry and that the economy needed to be overhauled.
"We were too exposed to financial services as an economy so the impact of the crash on the public finances was deeper on us than on others.
"We need a plan for change. A plan to reform the banks, invest in the industries of the future and support the small businesses and entrepreneurs who can be the lifeblood of our economy," he said.
Miliband, speaking at Labour's conference in Manchester, said he understood voters' anger that: "Labour hadn't stood up to the old ways in the City which said deregulation was the answer."
He said that it was wrong that a banker "earned more in a day than a care worker earned in a year".
Miliband said he would be pursuing a policy ensuring a "living wage" – higher than the current minimum wage – and urging wage restraint at the "top of society".
He also attacked Gordon Brown for boasting of an "end to boom and bust".
However, he also warned that he would have "no truck" with unions who acted irresponsibly.