Subrata Roy, head of the Sahara India conglomerate, was entering the Supreme Court building in New Delhi with scores of police and security guards when the man splashed him with ink, blackening his forehead and the side of his face.
"Subrata Roy is a thief. He has cheated and robbed us!" said the assailant, who was identified by Indian television channels as Manoj Sharma, a lawyer. Police detained Sharma and led him away.
India's securities regulator has accused Sahara India of raising nearly 200 billion rupees ($3.2 billion) through bonds that were later found to be illegal.
Investors have grown increasingly angry at Roy and are upset over what they see as his pampered treatment in custody. He has been staying in a plush forest guesthouse since his arrest and traveled to New Delhi for the court hearing in a luxury sedan, escorted by half a dozen police cars.
His company has been ordered to return billions of dollars to investors, many of whom are poor Indians who lost their life savings. Sahara India says its liability was much less and that it has already repaid many investors directly.
The court issued an arrest warrant for Roy last week after he missed a court date, saying his mother was ill. He surrendered to police on Friday and apologized to the court on Tuesday for his absence.
The Supreme Court on Tuesday ordered that Roy and two other directors of the company be sent to jail until further orders from the court. It fixed the next court date for March 11.
The court also directed Sahara India's lawyers to come up with a proposal for how it would pay back investors.
Sahara is well known throughout India because it co-owns a Formula One team and sponsors the Indian hockey team. It also sponsored the Indian cricket team until recently.
It has vast real estate holdings and interests in microfinance, media and entertainment companies and hotels, including the Plaza Hotel in New York and London's Grosvenor House. The company says its net worth is $11 billion.