It will be the first route between the Lithuanian and Polish cities in 76 years that will be operated without passengers having to change trains.
Lietuvos Gelezinkeliai (Lithuanian Railways) and Przewozy Regionalne signed a cooperation agreement on Tuesday.
"The route is being launched on Jun. 17," Lietuvos Gelezinkeliai CEO Stasys Dailydka said before the signing of the agreement.
The train service between Kaunas and Bialystok will be operated on weekends. A 4.5-hour trip will cost 11 euros.
The talks on the route were opened after a 120-kilometer section of the European standard gauge railway Rail Baltica from Lithuania's border with Poland to Kaunas was completed in October 2015.