In a letter to the Daily Telegraph leaders from some of Britain's household names like BP and Prudential sounded their support for Tory economic policy and warned of reversing cuts to corporation tax.
While by no means unexpected, the letter will be an especially bitter blow to the Labour leader, as five of the signatories are former Labour supporters.
Scottish entrepreneur and former Dragons' Den star Duncan Bannatyne, who previously supported Gordon Brown, joined the chairman of Dixons Carphone and Talk Talk Sir Charles Dunstone in praising the Tories' economic record.
Ed Miliband has regularly clashed with the business community over employment law, price caps and higher taxes. Stefano Pessina, the head of Boots, sparked a war of words with the Miliband after saying a Labour government would be a "catastrophe".
The Labour leader hit back, telling an audience:
You've now got this unholy alliance between the Conservative party and people like him (Pessina) who are saying the country can't change.
The Labour party lags significantly behind the Conservatives in terms if business support. According to a poll conducted by YouGov, 61 per cent of business leaders said a Labour government would be bad for Britain's economy.