A Big Brother spokesperson confirmed earlier today that Kay had departed the show in the earlier hours of this morning (Tuesday).
They said in a short statement: "Kay decided to leave the Big Brother House in the early hours of this morning. The other Housemates are aware."
Kay's exit followed her threatening to walk for the third time in the first two weeks in Monday night's highlights show.
Kay had begged to leave at gone midnight and threatened to breakout the fire door after rows with Lewis Flanagan and Cameron Cole.
In this evening's show, Kay was seen sleeping in Big Brother's spare room before returning to the house following the arguments.
She told Big Brother: "I'm going to go in the house and see what the atmosphere is like... I just have to do mentally what the right thing is for me.
"I don't want to get into conflicts with Cameron or Lewis. I don't think much can be achieved there. I'm not going in to start fighting. I want to relax and see what happens."
However Kay found herself clashing with Lewis again as they try to clear the air.
She told him: "I can't force it. I'd rather just move on as if it didn't happen. I feel really sensitive right now."
"It's impossible to speak to you because you make it seem like I'm trying to tear things out of you," he replied as the pair's chat got heated.
Kay later complained to Big Brother in the Diary Room: "I can't be in this house with Lewis."
Kay asks to leave but BB responded: "Big Brother is asking that you sleep on it..."
However Kay - one of five housemates currently up for eviction - reacted: "I'm not sleeping on anything. I'm sorry, no, I need to get out. I'm f**king done. This becoming some sick game. I need to get out please.
"This is against my will. You are keeping me in a place with people who aren't stable. He won't leave me alone."
Kay eventually returned to the house for one last time before packing her bags to leave.
There were tears in the house as the group said their goodbyes for good, with both Zoe and Brooke particularly hard hit.
Also upset was Cameron, who was given a pep talk by Lewis F.
Big Brother 2018 airs Sunday-Fridays night at 10PM on Channel 5.