Mustafizur has been granted an NOC from July 20 to August 20, making him available for the tournament from start to finish.
Expressing his excitement ahead of his maiden appearance in England's 100-ball competition, Mustafizur said in a video message: "I am Mustafizur Rahman. I can't wait to play for Birmingham. See you all very soon."
The Hundred begins on July 21, with Mustafizur set to become the first Bangladeshi cricketer to feature in the tournament.
Birmingham Phoenix signed the left-arm pacer for his £100,000 base price during The Hundred draft. He will also play for a franchise co-owned by England football star Jude Bellingham, who recently purchased a minority stake in the team worth around £1 million.
