Howard Fredrics, who worked at the university as senior lecturer of music between 2003 and 2006, was convicted at Kingston Magistrates' Court of harassing Sir Peter Scott via postings on a website, www.sirpeterscott.com.
Dr Fredrics was found guilty in his absence, having failed to appear for the hearing last month, and a warrant was issued for his arrest. He will be sentenced later this month.
At the trial, Sir Peter said the site was "intended to embarrass and humiliate" him and that some of its material, such as an allegation that he was a friend of former Prime Minister Tony Blair, was inaccurate. He added that he had met Dr Fredrics only five times.
Finding Dr Fredrics guilty, Judith Jewell, chairman of the bench, said: "We believe the course of conduct he pursued in setting up this website was intended to harass Sir Peter Scott ... he ought to have known that such actions would amount to harassment."
Dr Fredrics has used the site to expose controversial practices at Kingston in recent years. In 2008, he posted a recording of lecturers pressurising students to inflate their National Student Survey responses.
Sir Peter complained to the World Intellectual Property Organisation that Dr Fredrics was infringing his right to the domain name www.sirpeterscott.com. In May 2009, it ruled that the vice-chancellor had no rights to the name.
In a statement issued after the trial, Dr Fredrics says the conviction had been handed down despite a "compelling police report that indicated there was no evidence that the site contained anything that could lead to such a charge".
The report, seen by Times Higher Education, says the "sites listed do not contain content that is consistent with any harassment".
A second charge against Dr Fredrics of threatening and abusive behaviour following an encounter with Sir Peter in Kingston last year was put on firstname.lastname@example.org