Hubert lost his life after being involved in a lap 2 collision with Juan Manuel Correa through Radillion at the Circuit Spa-Francorchamps.
Hamilton stated that his "prayers and thoughts are with you and your family today”, and described the 2018 GP3 champion as a "hero".
“If a single one of you watching and enjoying this sport think for a second what we do is safe [you’re] hugely mistaken,” he wrote on social media.
“All these drivers put their life on the line when they hit the track and people need to appreciate that in a serious way because it is not appreciated enough. Not from the fans nor some of the people actually working in the sport.
“Anthoine is a hero as far as I’m concerned, for taking the risk he did to chase his dreams. I’m so sad that this has happened. Let’s lift him up and remember him. Rest in peace brother.”
Bahrain International Circuit - Winter testing