The Duke of Sussex sat down for yet another one-to-one chat as he launched his controversial memoir, Spare.
The Duke, 38, was seen joking around with Tom Hanks at the start of the show, before sharing a drink with Colbert.
He then went on to address comments surrounding his explosive book.
Harry denied boasting about killing 25 Taliban members in Afghanistan after he disclosed the number in his book Spare.
In a preview for the interview, he explained that he shared it to help other veterans.
He said: “I made a choice to share it.
“Having spent nearly two decades working with veterans all around the world, I think the most important thing is to be honest and be able to give space to others to be able to share their experiences without shame.
“My whole goal and my attempt with sharing that detail is to reduce the number of suicides.”
He previously said he opened up about killing dozens of militants in an attempt to “heal” himself and others.
But war heroes have scoffed at Harry’s claims he had to reveal his kill count as part of therapy.
Last night Stephen Colbert told his audience: “You might like it especially tomorrow when my guest will be Prince Harry, the Duke of Sussex.”
The audience then reacted with a collective “ooo”, as the host then joked: “Prince Harry will be here to talk about his new memoir Spare, also available on audiobook and commemorative plate.”
He mockingly continued: “I’ve read the book. It’s very enjoyable. Quite emotional, quite revealing.
“I’m going to have so much to talk about with His Harryness.”
He then referenced a moment when Prince Harry told Anderson Cooper that older brother Prince William wanted them to act like they didn’t know each other at Eton.
Colbert joked: “That’s heart-breaking. To be rejected by your older brother at school even though the magic hat sorted you into the same house.”
And he went on to tell the Firm: “Stock up on corgis and steal a priceless cultural treasure from one of your colonies because The Late Show is going imperial.”
Harry was also seen downing tequila shots, according to fans in attendance for the recording, reports MailOnline.
It comes as…
Harry is on the show to promote his memoir which hit UK shelves today.
Spare has sparked fury over his claims that William physically attacked him, while his admission he killed 25 Taliban members during the Afghanistan war generated protests in Helmand province over the weekend.
And Harry, 38, is said to have “crossed Charles’s red line” after attacking the monarch’s wife while promoting the book.
Harry shockingly accused Camilla of leaking stories to the press and claims she launched a campaign to marry Charles to get the crown.
In an explosive section of the book the Duke tells of the King and Queen Consort’s relationship – and how he and William begged their father not to marry her.
Harry says he and William promised Charles they would welcome Camilla into the family – but the only thing they asked in exchange is that he didn’t marry her.
Harry claimed they approved of Camilla but begged Charles not to get married for a second time following the death of their mother Diana.
Charles did not respond, he alleges.
Harry also sensationally confessed to snorting cocaine several times in one particularly shocking segment of the book.
He also admits smoking cannabis at Eton and experimenting with magic mushrooms.