Morell, who cast Trump as an unwitting agent of Putin in a New York Times op-ed last week
, said on ABC's "This Week" that he's comfortable with Clinton after seeing her in action in President Barack Obama's administration.
"I worked with her for four years very closely when she was secretary of state and I was at the CIA. I provided her -- personally provided her some of the most sensitive information that the Central Intelligence Agency has," he said. "She never misused it. She always protected it."
He added: "I would trust her with the crown jewels of the United States government. And, more importantly, I would trust her with the future security of the country and the future security of my kids."
His endorsement could help Clinton amid renewed criticism over her use of a private email server.
Morell also said he believes Putin -- "a trained intelligence officer, worked for the KGB, very talented, manipulated people much smarter than Donald Trump" -- has intentionally been using Trump's ego as a way in with the Republican nominee.
"He played this perfectly, right. He saw that Donald Trump wanted to be complimented," Morell said. "He complimented him. That led Donald Trump to then compliment Vladimir Putin and to defend Vladimir Putin's actions in a number of places around the world."
"And Donald Trump didn't even understand, right, that Putin was playing him. So, in Putin's mind, I have no doubt that Putin thinks that he's an unwitting agent of the Russian Federation, although Putin would never say that," he said. "From Mr. Trump's perspective, right, he simply heard Putin compliment him. He then responded by complimenting him. He never thought that he might be being played."
Trump pushed back against Morell Sunday night, tweeting, "Michael Morell, the lightweight former Acting Director of C.I.A., and a man who has made serious bad calls, is a total Clinton flunky!"