Ami Koshimizu made her voice acting debut in Ashita no Nadja as Nadja Applefield in 2003. She won the 1st Seiyu Awards in 2007 for Best Actress in a supporting role and currently operates under her own agency Office Restart, formed in 2022.

Her notable roles include:

• Code Geass – Kallen Stadtfeld
• Kill la Kill – Ryuko Matoi
• Suite PreCure – Hibiki Hojo/Cure Melody
• Danganronpa – Ibuki Mioda
• Sailor Moon Crystal – Sailor Jupiter