The crash occurred on the N83 road between Claregalway and Tuam at approximately 11.40pm.
Emergency services attended the scene, but the motorcyclist was pronounced dead at the location. His remains have since been taken to University Hospital Galway, where a post-mortem examination is expected to be carried out.
The section of the N83 affected by the incident remains closed while Gardaí conduct a forensic examination. Local diversions are currently in operation.
Gardaí are appealing to anyone who travelled along the road between 11pm and 11.40pm last night and may have witnessed the incident or noticed anything unusual to contact them.
Anyone with dashcam footage or other information that could assist the investigation is asked to contact Oranmore Garda Station on 091 388 030, the Garda Confidential Line on 1800 666 111, or any Garda station.
Investigations into the circumstances surrounding the collision are continuing.
