Napolitano has previously signaled that he's receptive to such an action against President Obama, which thus far has largely gained traction in fringe right-wing circles.
But on Thursday, when asked by Fox host Neil Cavuto what Republicans should do about Obama's executive actions, Napolitano didn't mince words.
"Impeach him," he told Cavuto.
Although impeachment may carry "odious connotations," Napolitano said, the House GOP's lawsuit against Obama will be "laughed out of court."
"The remedy for this type of behavior, which causes the law to change materially, is right there in the Constitution," Napolitano said.
But Napolitano said that even though there's "plenty" of legal grounds for impeachment, he expressed doubt that there's much of a political appetite.
It isn't totally uncharted territory for Napolitano. In June, he said that Andrew McCarthy, who has the impeachment market pretty much cornered, had made "a very, very valid argument people are going to start talking about."
At the time, it was the prisoner swap that secured the release of Sgt. Bowe Bergdahl that had Napolitano thinking that Obama had committed a crime.