English and history teacher James Boyle wanted to be allowed back into the classroom after his second trial ended with a not proven verdict.
But after hearing evidence from one of his victims, the General Teaching Council for Scotland (GTCS) decided Boyle, 56, was guilty of rape.
The GTCS then turned down Boyle's application to be allowed to resume his teaching career.
The evidence from Boyle's victim was heard in private but the woman was said to be "visibly distressed" at having to testify against him yet again.
Boyle, from Rutherglen, South Lanarkshire, was jailed for 12 years in 2005 for the rape and sexual abuse of children dating back to the 1970s.
The Appeal Court ordered the retrial after hearing claims he was not properly represented by his defence at the original trial.
At his retrial in February 2010 Boyle, who has always insisted he was innocent, was cleared. He said the allegations against him were made up and his alleged victims' evidence was a "foul distortion" of the truth.
The GTCS said it heard from a witness, named only as Mrs A. She said Boyle raped her and subjected her to horrific sex abuse when she was as young as seven.
The GTCS panel, on a majority verdict, found proven a charge of using "lewd, indecent and libidinous practices" against the woman on several occasions between 1970 and 1975.
A charge that Boyle, who taught in Glasgow, threatened to kill Mrs A and raped her was also found proven on a majority verdict.
The decision by the GTCS was made on the "balance of probabilities" rather than the higher standard of proof required in a criminal court, that of "beyond reasonable doubt".
Boyle was not present and not represented at the hearing.
The GTCS said in its report on the private session: "The Panel accepted the evidence of Mrs A as credible and reliable.
"The witness was visibly distressed at the ordeal of giving evidence for a fourth occasion in connection with the allegations.
"She described in some detail the incidents that had occurred when she was a young child of between seven and 12 years of age.
"She described the behaviour of the Respondent [Boyle] towards her at that time. She related the events as commencing at the age of seven shortly before her first holy communion and described her anxiety at that time due to his behaviour."
The woman said the abuse continued for five years, and he threatened her not to tell anyone about it.
The panel said that as a majority it "accepted on a balance of probabilities that the allegations had been proven".
Two more of Boyle's alleged victims had been due to give evidence to the GTCS, but they did not attend and charges relating to them were not considered.
Branding him "unfit to teach", the panel said: "Although of some antiquity, [the charges] were sufficiently serious to satisfy the Panel that the Respondent's conduct fell significantly short of the standards expected of an applicant for registration."