In June 2008, Spirit Airlines made a WARN (Worker Adjustment and Retraining Notice) application to potentially relocate or lay off hundreds of pilots and flight attendants, and the closure of their San Juan and LaGuardia crew bases. In 2006, Spirit exercised options to order 30 Airbus A320-200 aircraft for further expansion. This included a complete transformation of the business model and a public offering in 2011. In 2006, following an investment by Indigo Partners, Baldanza was elevated to the CEO role and held the position for 10 years. In January 2005, Ben Baldanza was hired as the President of Spirit, with the goal of making the company profitable. In 2007, Spirit filed DOT applications to offer service to Costa Rica, Haiti, the Netherlands Antilles, and Venezuela. Spirit began service to Grand Cayman, San Francisco, and Boston in 2006. In the fall of 2003, Spirit resumed flights to Washington, D.C.'s Ronald Reagan Washington National Airport, which were suspended after the September 11 attacks. They implemented a fully integrated Spanish-language customer service plan, including a website and dedicated reservation line. In November 2001, Spirit inaugurated service to San Juan, Puerto Rico. Discrepancies were found in the marking and placarding of emergency equipment, passenger seats, storage areas and doors on eight of Spirit's DC9 and MD80 aircraft. In 2000, the US Federal Aviation Administration (FAA) fined Spirit Airlines $67,000 for violating federal regulations on cabin and seat markings and placards. Prior to the decision to move the headquarters to Miramar, Spirit considered Atlantic City, New Jersey, and Detroit, Michigan. It relocated its headquarters in November 1999, moving to Miramar, Florida, in the Miami metropolitan area. Spirit initially had their headquarters in Eastpointe, Michigan, formerly East Detroit, in Metro Detroit. At the time Spirit was utilizing DC-9 and MD-80 aircraft. In 1998, she became the first woman captain. In 1996, Janet Patton became Spirit Airlines' first woman pilot. In response to criticism, Spirit Airlines said it would make sure all paid customers would always be able to fly to their destination, even if Spirit Airlines had to book them on a competitor's airline. The overbooking occurred because Spirit Airlines had given incorrect instructions to travel agents, causing those tickets not to be valid, even though the customers had paid for the flights. In the summer of 1994, Spirit Airlines overbooked flights, and 1,400 customers' tickets were canceled. During the next five years, Spirit expanded further, increasing service from Detroit and adding service in new markets such as Myrtle Beach, Los Angeles, and New York City.

Flights between Atlantic City and Fort Myers, Florida, began in September 1993. In April 1993, Spirit Airlines began scheduled service to Orlando, Fort Lauderdale, and St. Scheduled flights between Boston and Providence began on June 15, 1992. Scheduled flights between Detroit and Atlantic City began on June 1, 1992. In May 1992, Charter One brought jet aircraft into the fleet and changed its name to Spirit Airlines. In 1983, the airline service was founded in Macomb County, Michigan, by Ned Homfeld as Charter One Airlines, a Detroit-based charter tour operator providing travel packages to entertainment destinations such as Atlantic City, Las Vegas, and the Bahamas. In 1974, the company changed its name to Ground Air Transfer, Inc.

The company started as Clippert Trucking Company in 1964.

However, the United States Department of Justice has sued to block the deal. JetBlue has made an offer to acquire Spirit Airlines. Spirit was the seventh largest passenger carrier in North America as of 2023, as well as the largest ultra-low-cost carrier in North America. Spirit operates scheduled flights throughout the United States, the Caribbean and Latin America. (stylized as spirit) is a major United States ultra-low cost airline headquartered in Miramar, Florida, in the Miami metropolitan area.

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