The company has signed a purchase agreement for the CS300 variant of the twin-jet.
Republic Airways Holdings says the aircraft will be configured with 138 seats, in a single cabin arrangement.
The Indianapolis-based company owns several US operators including Chautauqua Airlines, Frontier Airlines, Lynx Aviation, Midwest Airlines, Republic Airlines and Shuttle America.
Deliveries are to begin in the second quarter of 2015. The aircraft will be fitted with Pratt & Whitney PW1000G engines and the carrier has signed an exclusive 15-year maintenance deal with the engine supplier.