Police said the man, who was her neighbour, was angry when he heard that her marriage had been fixed.
He quarrelled with the woman when she was waiting for a bus near her college at Naduvapatti and stabbed her. When she raised an alarm, he fled.
Some passers-by rushed the woman to a nearby hospital with stab injuries in her hand, the police said.
The man has been arrested.
He told the police that he was angry with her as she had rejected his marriage proposal.