Mesa officials say Phoenix-Mesa Gateway Airport is getting service from a third airline.
Frontier Airlines will join Allegiant and Spirit in serving Gateway, which has been developed on the site of the closed Williams Air Force Base in suburban Mesa.
Monday's announcement followed about a year of negotiations and the addition of the Denver-based carrier will triple the number of destinations reachable from the airport.
The 138-seat Airbus A319 will begin service to Denver on November 15, with one flight per day. $69 introductory fares are now available FrontierAirlines.com, according to the airline.
The flight would leave Denver at 1:10 p.m. and arrive at Gateway, then depart for Denver at 3:40 p.m.
Frontier flies to 80 cities in the U.S. International destinations include cities in Mexico, the Caribbean and Costa Rica.
"We think the demand is going to be terrific," said Frontier's Greg Aretakis.
"Airline planning people tend to take a map and draw a circle around an airport and say how many people are in that circle. And within 10 miles of this airport, there's over half a million people, which makes it one of the densest submarkets in the country."
Mesa Mayor Scott Smith says having Frontier as a third carrier legitimizes the airport.
Las Vegas-based Allegiant Air began serving the airport in 2008, and Florida-based Spirit Airlines since earlier this year.
Gateway already serves more than a million customers a year.
Phoenix Sky Harbor International Airport is the principal airport serving the metropolitan area.
The Associated Press contributed to this report.