Billionaire Knicks owner James Dolan revealed he’s the “secret billionaire” backing independent candidate Diana Florence’s bid to oust Manhattan District Attorney Alvin Bragg — as the ex-prosecutor vowed she’ll get tough on repeat offenders.

“We’ve heard from the beginning, from Mr. Bragg, that Diana has a secret billionaire supporter — here I am,” Dolan said in an exclusive interview alongside Florence at Madison Square Garden Monday afternoon.

“We are fully supporting Diana’s candidacy because of what’s happened the last four years, and what we’ve seen here,” he told The Post, referring to “violent crimes” he said have occurred on the streets outside the world-famous Midtown arena. 6

Florence, a veteran of the Manhattan DA’s Office who spent 25 years as a prosecutor, is “the ri

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