Rylan hosted the Big Brother spin-off show from 2013 up to its cancellation in 2018.
Taking to social media at the weekend, Rylan shared sad news that a former regular fan on the series had passed away.
"Just been informed of some very sad news. Our #BBBOTS audience regular lovely Karen has sadly passed away," he wrote.
Sharing a picture of Karen, Rylan added: "She was an amazing lady we spent many shows with and I’m gutted to hear this news, sending all my love to Nicola and the family.
"Rest in Peace beautiful xx"
A caption on the image read: "It is with deep regret that we wish to inform you that our beloved sister Karen Cummings, 47, has sadly passed away.
"She is survived by her father Leon, brother Anthony and family, three sisters Rosemary, Tracey and Nicola and her niece Chantelle. "
Karen's sister Nicola, who also appeared on BOTS, said on Twitter: "Thank you Rylan and everybody for your kind messages"
"Thinking of you," replied Rylan alongside a heart emoji.
Others who knew Karen were quick to share their fond memories.
One wrote: "So sad- she was an epitome of what BBBOTS was fun, fun, fun and a shining example of how to treat your fellow person. Always greeting you with a fabulous smile and kind word. Love to Nicola and the family. The Saplers xx"
Another added: "My deepest condolences to her family. Karen was a lovely lady. I had the pleasure of knowing and working with her for about 2 year. We used to talk about her Caribbean background and laugh. RIEP Karen."
Bit On The Side aired on Channel 5.