Speaking to Marty Morrissey on Virgin Media’s
The Six O’Clock Show, she asked for a photo of her mother Brenda to be shown to viewers, so they could “see how gorgeous” she was.
“My mum passed away suddenly two weeks ago. It was very unexpected,” she said.
“So the last couple of weeks, [as] I'm sure anyone who's gone through a sudden loss [knows], it's just been completely surreal.”
"Can we show a picture just so everyone can see how gorgeous my mum was. This is me and my brother and sister. We celebrated her on Mother's Day."
The TV presenter said she has received so many messages since her mother died, and that they’ve been a great comfort.
“The weird thing is that since restrictions lifted, we almost made such a point of packing in as much memories as we could with mum,” she said.
“So, I nearly have a picture of every single time I saw her over the last year and every special occasion we had.
“So that's been an amazing comfort to us as has all the messages that I've gotten from colleagues in front of the screen and behind the lens, from school mums to old friends, to family, to my husband.
“The kids have been unbelievably resilient, a bit too resilient actually. I'm like 'Be more sad, I can't be a normal mum right now'.”
Karen said she wanted to share the news on the show to explain why she she was feeling a bit shaky.
“What can you do? You get through it and you put one foot in front of the other and it's a strange time,” she said.
“She was a massive fan of the Six O'Clock Show so we have lost a very loyal fan.
“I just wanted to say that I'm not great tonight, I'm a bit shaky and that's why.”
Marty, whose mother Peggy died six months ago, tried to comfort Karen, and told her that her mother is always with her.
“I didn't know this had happened but she's with you all the time, there's no doubt about it,” he said.
“It's a tough journey, there's no point in denying it. My mother was in an accident and I miss her dearly. When I go home that's my biggest problem, there's a void and pain there.
“But you’ve got to keep going. It's like a rollercoaster, you're up and down. The loneliness is tough at times but you think of her and what she'd want you to do.
“And she'd want you to get on with the show and be Karen.”
Brenda Koster passed away unexpectedly at her home in Killiney, Co Dublin, on May 29.
A notice on RIP.ie reads: “Brenda, cherished wife and best friend of Herman, adored mother of Greg, Zoë and Karen.
"Deeply missed by her husband, children, sons-in-law Tiernan and John, daughter-in-law Caroline, her treasured grandchildren Ella, Callie and Aaron, Finn, J.J. and Eve, her sister Doreen, brothers-in-Law Sjaak and Rob, extended family and close friends.”