He tweeted: "Such incredibly sad news today".
Her death comes shortly after Louis released a new song titled "Two of Us" about him and his mom which included the heartbreaking lyrics: "You'll never know how much I miss you/the day that they took you/I wish it was me instead".
The 27-year-old singer was due to sing Two Of Us on the show, which is a song about Louis's grief over the death of his mum Johannah in 2016.
Watford boyband Rak-Su, who won the fourteenth series of the X Factor before Tomlinson debuted as a judge, sent their sympathies.
President Donald Trump meets Arlene Foster in Washington
Mr Trump has said he will be visiting the Republic of Ireland at some point this year. "I predicted it was going to happen". Mr Trump was due to visit the Republic of Ireland previous year , but it was cancelled for "scheduling reasons".
"A female believed to be aged 18 was pronounced dead at the scene", the statement said.
A person who was with the teenager called 999, according toThe Sun newspaper.
Felicite had more than 1 million followers on Instagram and had recently said on social media that she had stopped drinking and smoking cigarettes.
Her last social media post came on Sunday (March 10).
It is understood that Tomlinson, who is reportedly in London for a now-cancelled appearance on Friday night's Comic Relief, was told of her death on Wednesday.
At the time he described the performance as "harder than I ever imagined".