The collision happened close to The Stump pub, between Cirencester and Northleach, just before 1.15pm yesterday, Sunday, May 14.
The motorcyclist was a man from the Oxford area who was in his 50s.
His next of kin and the coroner have been informed.
No one else was injured in the collision.
The road was closed between Cirencester and Northleach until this morning (Monday, May 15) while a collision investigation took place.
Officers are asking anyone with any information about this incident to contact them by completing a form on the Gloucestershire Police website quoting incident 208 of May 14.