WRKO-AM pulled host John DePetro from the air after he made the comments Thursday. The station announced Friday that he had been fired.
"In the context of what he said and the tone with which he said it, the comments were completely inappropriate, derogatory and will not be tolerated," said Jason Wolfe, the vice president of AM programming and operations for station owner Entercom Boston.
DePetro did not immediately return an e-mailed request for comment Friday. However, he told The Boston Globe in a story posted Friday on its Web site that he was "stunned" that he had been fired.
He said he had called the candidate, Grace Ross, to apologize for calling her a "fat lesbian."
The host, who calls himself the "Independent Man," said he made the remark because he was exasperated that Ross and independent candidate Christy Mihos were eating up time during a debate earlier in the week that included Republican candidate Kerry Healey and Democrat Deval Patrick.
He said it was then that he told listeners he wished someone would "tell the fat lesbian to shut up."
"I just think both her and Christy have served their purpose, and I had a problem with them still thrusting themselves into the debate," he told the Globe. "I think I vocalized what a lot of people were thinking — will you just shut up and let them go at it. I added a little more."
Ross, who is openly gay, laughed when she heard about it but said the comment was offensive.
"Big, fat? I guess that's supposed to be his way of saying he doesn't like somebody," she said.
After hearing DePetro had been fired, she said: "I think that the comment was offensive in general, so I hope that many people in the state were offended by it and will help set a standard of what political debate is supposed to be about."
DePetro had also been reprimanded by station management in July for using a slur often aimed at gays in reference to Matt Amorello, the former chairman of the Massachusetts Turnpike Authority.
Wolfe said that after DePetro was suspended in that case, the host was warned that "any further comments of this kind would be dealt with in a severe way."
"I have no doubt that terminating John's employment was the right action to take," he said.