The confession comes after a former Pasadena City College student wrote in a blog that she had sex with Hugo Schwyzer in his campus office in 2011.
Schwyzer had previously denied the claims but admitted the allegations were true on his website Thursday.
On his blog, Schwyzer released the following statement: "Until recently, I maintained that I had stopped having sex with students enrolled in my classes in 1998. That is not true; I started sleeping with students again in 2008, well before my psychiatric breakdown of earlier this year. I have no intention of naming names or of discussing numbers, safe to say that the allegations (the student) makes are true and that I did indeed have sex with more than one adult student. There is no excuse for this behavior, and I do not expect anyone to defend it."
The woman in question was of age during the alleged relation.
Pasadena City College released a statement Thursday saying it will investigate the claims and hold Schwyzer accountable for his actions while an employee.
Schwyzer taught a class titled "Navigating Porn" last semester and invited adult film stars James Deen and Jessica Drake to speak to students.
The latest update on Schwyzer's website claims the professor is on an extended hiatus from teaching and is focused solely on his mental health.