Hackers stole customers' information from the website
and released it to the public this week, exposing something Duggar tried to keep secret.
"I have been the biggest hypocrite ever. While espousing faith and family values, I have secretly over the last several years been viewing pornography on the internet and this became a secret addiction and I became unfaithful to my wife," Duggar said in a statement Thursday.
He did not specifically address Ashley Madison in his statement, which was issued in the wake of the hackers' data dump and later modified to omit the reference to pornography.
"I brought hurt and a reproach to my family, close friends and the fans of our show with my actions that happened when I was 14-15 years old, and now I have re-broken their trust," Duggar said.
Earlier this year, Duggar was forced to apologize
after reports emerged alleging he molested girls as a teenager, including his sisters. He said then that he "acted inexcusably."
Duggar, 27, is the oldest of the children who appeared on TLC's hit show "19 Kids and Counting." The show has since been canceled.
According to an analysis from the cybersecurity company Trustify, Duggar paid Ashley Madison some $986 between 2012 and 2015. He used the name, josh_the_man, and described himself as an "attached male seeking female," according to the analysis.
Duggar reportedly listed some of his desires as: conventional sex, experimenting with sex toys and one-night stands. He listed travel and photography as personal interests. He said he was turned on by professional, confident women who dislike routine and have a secret love nest.
"As I am learning the hard way, we have the freedom to choose to our actions, but we do not get to choose our consequences. I deeply regret all hurt I have caused so many by being such a bad example," Duggar said in his Thursday statement. "I humbly ask for your forgiveness."
The Duggars are known for being devout Christians who don't believe in practicing birth control and whose children follow strict courtship rules.
Ashley Madison, which is owned by Avid Life Media, is designed to help married people cheat on their spouses. Its slogan is "Life is short. Have an affair."