The 21-year-old, who is widely regarded as one of the best young goalkeepers in world football, is currently in his third successive season on loan at Atletico Madrid.
As it stands, he will return to Stamford Bridge next season, but talk of a permanent move to Barcelona has also been mentioned.
"We must wait, time will tell. This year I wanted to stay at Atletico because I wasn't sure if I would play at Chelsea. Besides, I was excited to play in the Champions League with Atletico and wanted to be a starter with a view towards the World Cup," he told Sportium.
"But now everything depends on Chelsea. I had a conversation with [Jose] Mourinho and decided it was best to stay here. I belong to Chelsea, but Atletico are the most important club of my life. I've got titles and prestige in a short time."
Courtois joined Chelsea from Genk in 2011.