On television, Jim Marchese is the trash-talking bad boy from “The Real Housewives of New Jersey.” His off-camera role is lesser-known but still lucrative: Mr. Marchese is a whistleblower who twice has collected seven-figure awards for tipping off authorities to corporate wrongdoing.

The small mortgage firm Mr. Marchese owns in Shrewsbury, N.J., most recently collected $8.5 million for helping kindle the Justice Department’s record $16.65 billion settlement last summer with Bank of America Corp. , which was accused of selling shoddy mortgage investments in the run-up to the financial crisis.

Before that, in 2007, Mr. Marchese received $1.6 million after reporting his former employer, a Seattle pharmaceuticals firm now called CTI BioPharma Corp. , for allegedly defrauding Medicare.

“I’m trained as an attorney, I’m Sicilian, and I’m from New Jersey,” said Mr. Marchese, 45 years old. “If I see you kick a puppy, I’m going to say something. It’s not within me to not say something.”

Whistleblower lawsuits allow ordinary citizens to sue on behalf of the U.S. government. If a case is successful, the tipster can receive a portion of the settlement money. Since the financial crisis, many whistleblower complaints have targeted financial institutions, and the government has paid tens of millions for insider tips that led to settlements against UBS AG , GlaxoSmithKline and other firms. The Justice Department also relied on a whistleblower in its mortgage-securities investigation against J.P. Morgan in November 2013.