Reni Raion (Ukrainian: Ренійський район; Romanian: Raionul Reni) was a raion (district) in Odesa Oblast in south-western Ukraine, in the historic Budjak region of Bessarabia.

The raion was predominantly Moldovan and the Ukrainian language was rare.

The raion of Reni, in its boundaries at that time, including the city of Reni, had 40,680 inhabitants in 2001, including 19,938 self-identified Moldovans (49.01%), 7,196 ethnic Ukrainians (17.69%), 6,136 ethnic Russians (15.08%), 3,439 Bulgarians (8.45%), 736 Gagauz (1.81%) and 36 self-identified Romanians (0.09%).

[8] The city of Reni had 20,761 inhabitants in 2001, including 6,694 ethnic Ukrainians (32.24%), 6,126 self-identified Moldovans (29.5%), 5,589 ethnic Russians (26.92%), 1,012 Bulgarians (4.87%), 736 Gagauz (1.81%) and 22 self-identified Romanians (0.11%).

[9] The city of Reni was mostly (70.54%) Russophone, 13.37% Romanian-speaking, 12.5% Ukrainian-speaking, 1.52% Gagauz-speaking and 1.33% Bulgarian-speaking.