The 2022 Ballon d'Or winner felt a strong pain in his thigh during a sprint toward the end of the training session.
After undergoing an MRI, it was confirmed that Benzema had suffered a muscle tear that would need three weeks of recovery time.
The 2022 World Cup, which begins on Sunday and runs through the final on Dec. 18, will now be the first since 1978 not to feature the reigning Ballon d'Or winner.
France begin the defence of the World Cup title they won in 2018 when taking on Australia on Tuesday. Per FIFA rules, they will have until 24 hours before their first game to name a replacement to their squad.
Benzema was France's top scorer at the 2014 World Cup but did not play in their victorious 2018 World Cup campaign because he was still exiled from the team for his alleged role in a sex-tape scandal with then-France teammate Mathieu Valbuena.