The 72-year-old journalist - who lives in France - told viewers of his 8pm slot on the new current affairs channel that he would be taking a "few weeks" off and would be replaced on his primetime show by former Sky News presenter Colin Brazier.
Neil closed his show on Thursday 24 June saying: "That’s it for tonight and from me for the next few weeks. But I leave you in the safe and professional hands of Colin Brazier.”
The former BBC political reporter promised viewers: "I’ll be back before the summer is out and when you least expect it so stay tuned."
And he also took the opportunity to defend GB News over criticism it has received since it launched on 13 June.
Neil said: "Before I take this break, let me say this. Yes, we had a bit of a rocky start with the launch of GB News.
"We’re a start-up, they’re always a bit rocky these start-ups. But we are up and running as you can see, we get better every day and there’s clearly an appetite for what we’re doing.
"And in two short weeks, we’ve already built a loyal audience which has beaten all of our expectations, it’s often bigger than the other news channels and it’s growing.
"That’s the real story about GB News to date and you won’t often read that in the papers.
"So on behalf of GB News, I say to all of our viewers, thank you. We won’t let you down and you ain't seen nothing yet."
Since its launch GB News has hit several hurdles, including viewers complaining about poor sound quality, presenters falling victim to reading out prank names on air and companies suspending their advertising in reaction to a social media campaign against the channel's "anti-woke" ethos.
But the channel has also celebrated success in the viewing figures - scoring higher ratings than rival channels BBC and Sky News.
Neil bragged on Twitter: "Great figures on @GBNEWS Andrew Neil show last night. Number one in time slot (again). Three times audience of Sky News. 26% more than BBC News Channel. And we’ve only just begun."
GB News bills itself as being "anti-woke" and an antidote to the left-wing bias that Channel 4 and BBC News have been accused of. But Neil has denied it is a direct copy of America's Fox News.
He said previously: "That is an easy, inaccurate shorthand for what we are trying to do. In terms of format we are like Fox but we won’t be like Fox in that they come from a hard right disinformation fake news conspiracy agenda.
"I have worked too long and hard to build up a journalistic reputation to consider going down that route."
The Scottish journalist lives in France, but has homes in London and Scotland. He returned to the UK for the launch of GB News after spending lockdown during the coronavirus pandemic at his French residence.
Watch: Who said it - GB News or Fox News?