Felicité Tomlinson, her 18-year-old sister unexpectedly died of cardiac arrest.
The artist had already suffered the loss of his mother in 2016, after the fight against cancer.
The singer's sister was accompanied in her apartment London when he fell to the ground.
Immediately after receiving the emergency call, the ambulance personnel arrived, but they could not bring her to life.
Louis Tomlinson, the oldest of the seven brothers, who was working when he received the news, immediately canceled the presentations he had in the Comic Relief, a charity event organized by the chain BBC.
As reported in the British newspaper The sun, the musician "It has been destroyed."