After rumours of court proceedings against Zacharias, he posted a detailed response on his ministry website.
In it, he admitted to forming a relationship with a couple in Canada in order to support the husband who had questions about the Christian faith.
He said that relationship led on to the wife sending him "extremely inappropriate pictures of herself unsolicited".
Zacharias claims that after blocking her messages, she tried to blackmail him by claiming he had sought the pictures.
After settling the case out of court, Zacharias said he'd learned a "difficult and painful lesson".
"As a husband, father, grandfather, and leader of a Christian ministry I should not have engaged in ongoing communication with a woman other than my wife," he said. "I failed to exercise wise caution and to protect myself from even the appearance of impropriety, and for that I am profoundly sorry. I have acknowledged this to my Lord, my wife, my children, our ministry board, and my colleagues.
"Let me state categorically that I never met this woman alone, publicly or privately. The question is not whether I solicited or sent any illicit photos or messages to another woman - I did not, and there is no evidence to the contrary - but rather, whether I should have been a willing participant in any extended communication with a woman not my wife.
"The answer, I can unequivocally say, is no, and I fully accept responsibility. In all my correspondence with thousands of people in 45 years of ministry, I have never been confronted with a situation such as this, and God and my family and close friends know how grieved I have been."
Zacharias was forced to release the statement after a website was set up listing a number of allegations against Zacharias.
This website also accused him of making up his credentials which included him referring to himself as Dr Zacharias.
In a separate statement, his ministry RZIM said: "Neither Ravi Zacharias nor Ravi Zacharias International Ministries (RZIM) has ever knowingly misstated or misrepresented Ravi's credentials.
"When it has been brought to our attention that something was stated incorrectly with regard to Ravi's background, we have made every effort to correct it."
Ravi Zacharias has previously been awarded an honorary doctorate.