Eike Batista, once Brazil's wealthiest man, was banned by market regulators from serving as an officer of a publicly traded company for five years.
Brazil's securities and exchange commission CVM ruled that Batista broke conflict of interest rules by voting as a shareholder to approve the 2013 financial results of his OGX Petroleo e Gas SA oil company now Ogpar) while also serving as company chairman.
The announcement was made on CVM's website.
Defense attorneys for the flamboyant tycoon said they would appeal the ruling.
Batista, who has investments in mining and shipping as well as oil and gas, is also facing charges of stock market manipulation and insider trading.
A fallen icon of Brazil's boom years, he is suspected of having used inflated oil production goals to mislead investors in order to raise a billion dollars for OGX.
When the wells clearly could not produce enough, OGX declared bankruptcy in October 2013, with debts of around $4.6 billion.