The university confirmed Miller's decision to leave head coach Thad Matta's staff after serving under his former college mentor for six of the past seven years.
"We wish the Miller family well," Ohio State spokeswoman Alissa Clendenen said via email. "Brandon has been a significant part of Ohio State's success the last several years and he will be missed."
The 32-year-old Miller, who was a standout guard at Butler University from 1999-2003, held several positions during his time in Columbus. He was director of basketball operations in 2005 and '06 before taking over as video coordinator for the 2007 season.
After a season as an assistant coach at Butler, he returned to Ohio State in June 2007 to become an assistant to Matta, who coached him at Butler in 2002-03.
The school plans no further comment until the position is filled.