G9, G.IX, G09 or G-9 has several uses including:
- Group of Nine, a group of nine European states
- G9 (consortium), a group of nine Australian internet providers
- G9 (album), the debut album of rapper Gloc-9
- G9, a standard bipin lightbulb socket
- G9, or FRG9, short for Fòs Revolisyonè G9 an fanmi e alye (Revolutionary Forces of the G9 Family and Allies), a coalition of armed gangs in Haiti
- G9, the IATA airline designator for Air Arabia
- G9 star, a subclass of G-class stars
- Canon PowerShot G9, a digital camera
- County Route G9 (California)
- Gotha G.IX, a 1918 German bomber aircraft
- Group 9 elements of the periodic table
- HMS G9, a British submarine
- HMS Quilliam (G09), a 1941 British Royal Navy Q class destroyer
- Nachtjagdgeschwader 1, from its historic Geschwaderkennung code with the Luftwaffe in World War II
- Panasonic Lumix DC-G9, a mirrorless system camera body