Noel Biderman did not immediately respond to an inquiry about his departure, which Avid Life Media described as a "mutual" decision.
Earlier this month, personal information about millions of Ashley Madison customers, including e-mails, member profiles, credit-card transactions and other sensitive information, showed up online. A group known as Impact Team took credit for the hack, which is now under investigation by the FBI and Canadian authorities.
The information was initially only accessible on the dark Web, where users must use anonymous browsing tools. But soon after the hack, databases showed up on the broader Web allowing people to search some parts of the data.
Avid Life Media offered a $500,000 bounty for information leading to the hackers.
"We are actively adjusting to the attack on our business and members’ privacy by criminals. We will continue to provide access to our unique platforms for our worldwide members," Avid Media said in a statement.
"We are actively cooperating with international law enforcement in an effort to bring those responsible for the theft of proprietary member and business information to justice."