The service will run from May 1 through Nov. 1, officials said.
Officials touted the Spirit's expansion, which also opens a new route between Minneapolis-St. Paul and Houston, as a benefit to local residents and tourists.
"Continued growth from Spirit is good news for travelers from throughout the region," said Paul J. Wiedefeld, BWI's CEO, in a statement. "Spirit is adding more options and more low fares for our customers."
Spirit first "shifted" its service in the Baltimore-Washington area from Ronald Reagan Washington National Airport to BWI in September 2012, with service to Fort Lauderdale and Dallas-Fort Worth, said Jonathan Dean, a BWI spokesman.
The new route to Minneapolis-St. Paul is the latest expansion, after flights to Myrtle Beach and Las Vegas also were added.
Spirit said between May 1 and May 21, a flight will depart Minneapolis-St. Paul for Baltimore daily at 9:27 a.m., and a flight will depart Baltimore for Minneapolis-St. Paul at 1:36 p.m.
Between May 22 and Nov. 1, a flight will depart Minneapolis-St. Paul for Baltimore daily at 4:45 p.m., and a flight will depart Baltimore for Minneapolis-St. Paul at 12:05 p.m.