Miller, not to be confused with the recently retired sharpshooter, was named the G League's Coach of the Year in 2017-18 after leading the Westchester Knicks to a franchise-record 32 wins. He'll become New York's 13th head coach in the past 18 years.
This season marked Miller's first on the Knicks' staff.
Keith Bogans is also being promoted to work under Miller on New York's bench, the team confirmed. The former NBA veteran previously served on the club's G League coaching staff.
Miller's fellow assistant, Pat Sullivan, was also a candidate to replace Fizdale, sources told ESPN's Adrian Wojnarowski and Ramona Shelburne.