Rodrigo Lindoso scored after 20 minutes and Rafael Sobis got a second just after the hour mark to put Inter in command.
Fernandao took advantage of poor defending to get one back for the visitors with 12 minutes remaining but Andres D’Alessandro restored Inter’s two-goal cushion three minutes later.
The home victory, Inter's fifth straight, leaves them fourth in Brazil’s Serie A with 16 points from nine games. Bahia are seventh, two points behind.
Brazil’s league program will halt for a month from Thursday as the country hosts the Copa America.
(Reporting by Andrew Downie; Editing by Peter Rutherford)
