Celebrities and fans have taken to social media to praise the 40-year-old.
Laura Whitmore, who took over Flack as host of Love Island ahead of the current season, tweeted: "I'm trying to find the words but I can't" with a broken love heart emoji and a picture of the pair together.
Good Morning Britain host Piers Morgan wrote: "Caroline was a fun, bright & sparky person whose whole world collapsed recently, both professionally & personally.
"She told me it had been the worst time of her life, and was clearly struggling to cope with losing everything she held dear. This is such sad, awful news."
Martin Kemp wrote: "Caroline Flack, I’m so so sad to hear this News...All my love goes out to her family and friends..oh man!Rest in Peace Caroline!"
Geordie Store star Charlotte Crosby posted: "Caroline flack ? my heart is breaking this can’t be true."
Actress Jameela Jamil wrote: "It was only a matter of time before the media and a prolonged social media dogpile, hers lasted for MONTHS, pushed someone completely over the edge. Rest In Peace Caroline Flack."
Former Big Brother host Davina McCall was also among those to pay tributes to Ms Flack.
Zara Holland, a former Love Island contest, added: "Caroline Flack you supported me always, you were so kind to me & my family, I will never forget that. I spoke to you, and gave my support during the recent media intrusion. The media & trolls are killing people. Please THINK before you speak."
The Only Way Is Essex star Joey Essex tweeted: This beautiful girl had a good soul and a sweet heart... To hear this news today is honestly heart breaking. I send my love to all of Caroline’s friends and family. God bless and now you can finally rest in peace."
Guardian columnist Owen Jones wrote: "Utterly devastating news about Caroline Flack, and right now I hope all the people who loved her have support. Just horrible.
"The way she has been treated is utterly disgusting, and whatever the circumstances, I hope a lot of people are assessing their behaviour very hard."
And Match of the Day presenter and BBC Breakfast host Dan Walker said: "Awful news about Caroline Flack. We really need to be better at taking care of each other. So sad."
Chat show host Jonathan Ross said: "I am very sad to hear that Caroline Flack is dead. I had been in touch with her recently and had hoped she was doing better. She was talented and smart and likeable and she will he missed. It’s awful."