Leclerc won a tense Belgian Grand Prix by 0.9 seconds as Lewis Hamilton finished second, less than 24 hours after news of Hubert's death was confirmed by the Fédération Internationale de l'Automobile (FIA).
Leclerc had known Hubert since his early days in go-karting and raced against the Frenchman as early as 2005.
When he parked up after the race, the Ferrari driver pointed to the sky before directing the TV camera to a sticker on his car that read "Racing for Anthoine".
The mixed emotions were clear to see in Leclerc's body language and, speaking in parc ferme, he dedicated the win to Hubert.
"On one hand, a dream I've had since being a child has been realised," said Leclerc. "On the other hand, it has been very a difficult weekend since yesterday.
"We have lost a friend first of all. It is very difficult in this situation. I would like to dedicate my first win to him. We have grown up together. My first ever race I did with Anthoine when we were younger, there was Esteban [Ocon], Pierre [Gasly].
"I can't fully enjoy my first victory, but it will definitely be a memory I will keep forever."
Hubert's accident happened at Spa-Francorchamps' high-speed Raidillon corner, which follows the famous Eau Rouge corner. He crashed into the barriers before ricocheting into the path of another car, driven by Juan Manuel Correa, who suffered fractured legs and a minor spinal injury.
Hubert's death was the first to result from injuries sustained at a grand prix event since Leclerc's godfather, Jules Bianchi, died as a result of an accident at the 2014 Japanese Grand Prix. Leclerc was not racing in F1 at that time and said Hubert's death was the first time he had to get back in the cockpit so soon after a fatality at the same circuit.
"For me it was definitely the first situation like that where we lose someone on track and you need to race the day after," he said.
"It's obviously quite challenging to then close the visor and go through this exact same corner at the same speed you do the day before, but that's what you need to do at the end. So, yeah, that's what I tried to do today."