It is unclear if the retirement is immediate and it is unclear if Geiger is being forced out. President Karen Holbrook and Geiger will answer questions at the press conference.
Geiger, 65, is in his 11th year as director of athletics at OSU. He was hired April 29, 1994.
Ohio State's football media guide says Geiger's time at OSU has been a "Golden Era" for Buckeye athletics, resulting in new facilities, national championships, fiscal stability and academic excellence.
Geiger was also the AD at Brown (1971-75), Pennsylvania (1975-79), Stanford (1979-90) and Maryland (1990-94).
Bucknuts.com will have more on this breaking story later this afternoon.