Morgan asked Giuliani about a recent tweet written by the President, which used the phrase, "When the looting starts, the shooting starts."
Trump had sent the tweet following widespread rioting and looting in the US linked the protests and demonstrations over the last 10 days, as Americans reel from the killing of African-American man George Floyd by white police officer Derek Chauvin. The President's tweet was widely criticised as it was first used by a Miami Police department chief in the 1960s, who threatened to shoot African-American people in the community.
Both Morgan and Giuliani are strong supporters of Trump, with Morgan known to write opinion pieces supporting The President. Morgan used to be among one of the few people Trump followed on Twitter.
When asked about the tweet, Giuliani, who appeared agitated, replied, "It isn't inflammatory, it's accurate."
"You sound completely barking mad," Morgan said. "You've lost the plot."
"You were the one who was thrown off television, because you had ratings that were about two," Giuliani fired back.
"You keep going Rudy," Morgan said.
"I remember what happened to your show Piers, I remember the mistakes you made and I remember how you sucked up."
"It's really sad to see what's happened to you," Morgan said, also apologising for Giuliani's foul language. The pair later argued over whether or not Giuliani had sworn on air.
"It was really sad to see how your career imploded in the United States, Piers. If you think I have any respect for you after this, well, maybe you don't care.
"But everyone in America knows you're a failed journalist," Giuliani fired back.
"You've come on here, you've been rude and abusive," Morgan said towards the end of the interview.
"You sound unhinged. You've been using profanity and you were somebody I used to admire."