The FDNY touted its growing racial and gender diversity as more than 300 probationary firefighters graduated on Wednesday — but that didn’t stop a bigot from joining the department.

Among those giving the white-gloved salute in their new dress uniforms was Joseph Cassano, the son of former FDNY Commissioner Sal Cassano.

The younger Cassano resigned from his EMT job in 2013, after The Post revealed his racist online postings, including ones that referred to blacks by the derogatory term “shwoogs” and another that said, “I like jews about as much as hitler. #too far? nope!”

Cassano issued an apology when he resigned, stating, “These tasteless comments do not reflect the person my parents raised me to be.” He began training last month at the Fire Academy on Randalls Island.

He and his father refused to comment Wednesday.

On Wednesday, black probationary firefighters who were graduating with Cassano said they would take him at his word.

“With this job, it doesn’t matter what your past is as long as you own up to it, live by the oath and never leave your brothers or sisters behind,” said Jeffery Jovin, 28, of East New York, assigned to Engine 290 in Brooklyn.

Added Kerone Knowles, 30, of Jamaica, assigned to Engine 234 in Brooklyn: “What he did in the past, I can’t judge him for.”

Commissioner Daniel Nigro this week boasted that “people of color comprise 34 percent of the 311 graduating probationary firefighters,” and at Wednesday’s graduation ceremony he noted five women are among them, “which means more women than ever before are serving.”

“The FDNY has made a great many people in New York City unhappy and uneasy with the graduation of Joseph Cassano on Wednesday,” city councilman Andy King said Thursday.

“I am still in disagreement of his hiring and can only hope that he will serve the people of New York City without any prejudice in his heart, in his mind and in his spirit. I say this because he had exhibited a lot of bias and bigotry while working as an EMT in the FDNY only 5 years ago!”

Additional reporting by Susan Edelman and Laura Italiano