Emanuele Ferrero de Gubernatis Ventimiglia, 24, fought with Jamie Barr during a struggle at the bash last March.
Mr Barr, a former poster boy for VisitScotland, the national tourism agency, had been working at the St Andrews University Charity event.
A court was told he had tried to prevent Ventimiglia, wearing traditional German lederhosen, getting into a taxi with his girlfriend, who was dressed in a dirndl, a traditional Bavarian dress, after the couple had rowed.
Mr Barr, the court heard, was left needing a series of operations, including one that saw pieces of rib grafted to the side of his head. This enabled it to develop a new blood supply before having the ear reconstructed.
Despite admitting biting off Mr Barr's ear, Ventimiglia walked free after a trial at Kirkcaldy Sheriff Court.
A jury decided that Ventimiglia, who is originally from Turin but now of London, and is believed to be descended from Fiat founder Alfonso Ferrero de Gubernatis Ventimiglia, had acted in self-defence during the rammy and found the charge not proven.
The court had heard the event, labelled an Oktoberfest, attracts guests from across the world, as well as hundreds of students.
At this year's event a German princess, Theodora Sayn-Wittgenstein, was arrested and now faces a string of assault and racist breach of the peace charges.
Mr Barr, 49, told the jury he had previously finished ninth in the World's Strongest Man competition and helped promote Highland Games on posters distributed by VisitScotland in Germany.
He said he had been working as a first aider at the event, held annually at Kinkell Byre, near St Andrews, but had been helping at a taxi queue at the end of the night to clear a backlog of revellers.
Mr Barr said: "The night finished with someone biting my ear off - it wasn't entirely pleasant.
"I noticed there was a girl in the back of a taxi crying hysterically. She had her legs up trying to kick a guy away who was trying to get in the taxi. I asked if she was okay and asked if she wanted him in there. She said no. I told him he couldn't get in and he asked if I had a problem - he wasn't happy.
"I shut the taxi door and he appeared right in front of me."
He said that as he went to turn around, the other man appeared and put his head against his forehead. Mr Barr added: "I put my hands up to push him away - his head slipped down the side of mine.
"I felt him bite my ear and he came back towards me and scratched my face. I pushed him as he bit me, then butted him and punched him.
"Then I realised he had bitten a large chunk of my ear off - they found it on the ground, it just looked like a bit of rubber. I was taken to hospital with the piece of ear, but they couldn't re-attach it."
The jury was shown photographs of a huge piece of his left ear ripped off.
Mr Barr told the court he had undergone a series of operations - first having pieces of rib removed and sewn behind his ear to his head for a blood supply to be established.
Six months later a skin graft was taken from his arm to be stretched over the new ear cartilage and re-attached.
But Gordon Jackson, QC, defending, branded Mr Barr a "liar" - and said he had made up his version of events to paint Ventimiglia as the aggressor.
Ventimiglia said he had "never been in a situation like it" and was scared.
He nodded at the jurors as Sheriff Alistair Thornton told him he was free to go.