Dr Uchenna’s death was announced by her family on Friday, who wrote in an Instagram post that they were “heartbroken” to share news of her passing that day.
Holly took to her Instagram stories on Monday evening to remember the late star, writing that she was “unbelievably sad to hear of the passing” of her former colleague.
“We first worked together many moons ago with @oralb_uk and she was very kind to me… and then of course again, giving her advice on @thismorning.”
The presenter said she was sending “all my love to her family”.
Holly also commented underneath the post on Dr Uchenna’s account to say she was “so very sorry for your loss”.
Myleene Klass was also among stars who paid tribute in the comments, writing: “I can’t believe you’ve gone. I’m so sorry for your family, your daughter. RIP my friend x.”
BBC presenter Jo Wiley said that Dr Uchenna’s death was “devastating news”, adding that she was “sending love to her daughter, family and London Smiling team. Strong, beautiful, funny Uchenna. Awful. Just Awful.”
Author Candice Brathwaite also expressed her shock, writing: “What? I am reading but not comprehending”.
In the family’s Instagram post announcing Dr Uchenna’s death, they wrote: “We know many of you will be devastated and shocked to see this post.
“We ask for your prayers and some privacy at this difficult time. We will be in touch in the coming days.”
Dr Uchenna was a contributor on This Morning who also worked on TV shows including 10 Ways To Lose 10 Years, Morning Live and The Alan Titchmarsh Show.
She qualified at Guy’s Hospital and was an expert in cosmetic dentistry, running two dental practices in London.
Earlier this month, Holly led tributes to This Morning contributor Matty Lock following his death at the age of just 19.