GRT may refer to:
- Grease Removal Technology, or GRT- Lipase enzyme
- General Recorded Tape, aka GRT Corporation, a defunct corporation that owned Chess Records and Janus Records as well as being a label in its own right
- General relativity theory
- Gross receipts tax, a tax levied on the gross revenue of a company
- Gross Register Tonnage, a measure of the cargo capacity of a ship
- GRT Corporation, an American IT services provider headquartered in Stamford, CT
- Grand River Transit, a regional transit authority in the Region of Waterloo, Ontario, Canada
- Granular Recovery Technology