Tributes are pouring in for the "X-Factor" star Tom Mann’s fiancée Dani Hampson after she died one day after their wedding was scheduled to take place. 

Mann announced Hampson’s death on Instagram on Monday. "I can’t believe I am writing these words but my darling Dani - my best friend, my everything and more, the love of my life - passed away in the early hours of Saturday morning, 18th June," he wrote alongside an image of Thompson and their son, Bowie. 

"On what was supposed to be the happiest day of our lives ended in irreversible heartbreak." The 34-year-old publicist's cause of death is still unknown.

Danielle Hampson died before marrying fiance Tom Mann

Danielle Hampson died one day after what was supposed to be her wedding day to X-Factor contestant Tom Mann. (Instagram)

"My darling Dani, the brightest light in any room, my world is nothing but darkness without you. I will miss you forever," Mann concluded his caption.

He shared with his followers that he will "wear this ring that I was always supposed to wear as a sign of my unconditional love to you."

‘X-FACTOR’ CONTESTANT TOM MANN'S FIANCEE DANI THOMPSON DIES ON THEIR WEDDING WEEKEND

Since the tragic news was shared, celebrities have flooded social media with tributes to Hampson and condolences to their family. The couple share their son, Bowie, who was born in October.

The Spice Girls took to Twitter to remember Hampson by sharing an image of her during the Spiceworld 2019 tour. 

The group wrote, "We were very saddened to hear of the passing of Dani Hampson who was part of the Spiceworld 2019 family. Sending love and strength to Tom, Bowie and Dani’s family and friends," adding a red heart emoji.

Emma Bunton, a member of the iconic pop group, wrote a separate message on Mann's post and said, "Heartbroken for you. A beautiful soul that will live on. Thinking of you all."

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Singer Ellie Goulding commented on Mann's post and wrote, "I’m thinking of you non stop… You are so strong. Here for you always. Love you xxxx."

Musician Lewis Capaldi added "Love you brother" to Mann's post.

Ellie Golding

Singer Ellie Goulding shared a heartfelt message on Mann's Instagram post and said "I’m thinking of you non stop." (Photo by Naomi Baker/Getty Images)

Take That star Howard Donald, who worked alongside Hampson in 2017, said he was "gutted" to hear the news of her sudden passing.

"I’m gutted beyond words that one of our dancers on wonderland has passed away. What a beautiful and super talented dancer she was," he wrote. "I’m happy to say I danced with her and the uk dance world will be shocked and saddened just like I am."

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British singer Mimi Webb also took to Mann's comment section and wrote, "Tom I’m so so sorry. sending all my love to you & thinking of you. love you brother x we are with you."

"Girls Aloud" star Nadine Coyle added: "Sending so much love, light & healing to you, Bowie & everyone who loved Dani!!"

Television mogul Simon Cowell poses after receiving the British Academy Television Awards Special Award at the Palladium Theatre in London June 6, 2010. REUTERS/Luke MacGregor (BRITAIN - Tags: ENTERTAINMENT PROFILE SOCIETY)

Simon Cowell shared his condolences for Hampson. Cowell was a judge on "X Factor" while Mann was a contestant in 2014. (Reuters)

Mann auditioned for "X-Factor" as a solo singer in 2014, but producers formed the group "Stereo Kicks." Simon Cowell was a judge during Mann's time on the show and shared his condolences in a statement with TMZ.

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"As a father myself, I simply cannot imagine the heartbreak Tom and his family are going through and will be personally reaching out to him. From my family to his, we extend our deepest condolences and all of our love during this tragic time," his statement read.