Jetstar will fly direct between Adelaide and Bali three times per week from the middle of December.
The direct flights to and from Denpasar will cut up to five hours from the current travel time.
As part of the launch of the new service, cheap flights are on offer for travel between next May and July.
Virgin Australia already operates four direct flights each week.
David Hall of Jetstar said Indonesia was a hugely popular travel destination for Australians.