GB News has announced that talkRADIO's Patrick Christys has joined the station and will present a new show starting from next week.
Muroki will co-host the new show with Christys, while Brazier has been filling in for Andrew Neil in the flagship 8pm slot for the last six weeks.
"GB News is already changing the conversation and setting the news agenda rather than following it, which is exactly what I love doing most," said Christys.
"Mercy and I will not be afraid to tackle the punchy issues that Britons really care about but that are, too often, ignored by others. We'll dare to stand up and say what people are thinking."
Brazier's role at the station when Neil eventually returns from his extended summer break is currently unclear.