Buffalo Niagara International Airport opened as Buffalo Municipal Airport in 1926 on former farmland, making it one of the country's oldest public airports. The original airport included a small terminal building, one hangar, and four cinder runways, each 3,000 feet (910 m) long by 100 feet (30 m) wide. Passenger and mail service began in December 1927, with service to Cleveland. A WPA-built Art Deco V-shaped terminal with a large cylindrical tower opened in 1939, replacing the original terminal. At this time, the airport had four paved runways: Runway 5/23 was 5,630 feet (1,720 m) long, Runway 13/31 (now 14/32) was 5,730 feet (1,750 m) long, Runway 1/19 was 5,000 feet (1,500 m) long, and Runway 8/26 was 3,650 feet (1,110 m) long. All of the runways were 150 feet (46 m) wide. Runways 1–19 and 8–26 were closed in the 1950s, and Runway 13–31 was renamed Runway 14–32.

The terminal's first expansion was completed in 1955. This addition expanded the terminal to 11 gates, tripled the terminal's square footage and added a restaurant and lounge. In 1959, the airport was acquired by the Niagara Frontier Transportation Authority from the City of Buffalo and renamed Greater Buffalo International Airport.

The terminal received another overhaul in 1961 that added a new control tower and a concourse for American Airlines. The first scheduled jet service was American Boeing 727 service to/from New York in 1965; Runway 5–23 was extended northeast from 5,645 feet (1,721 m) to 8,100 feet (2,500 m) later that year. In 1968, an auxiliary terminal building, West Terminal, was announced. Construction began in 1969 and it opened in 1971 with nine gates. During this time, an all-new airport to be located in Wheatfield, New York was in the planning stages and so the West Terminal was intended to have a ten-year life expectancy.

Despite the addition of the West Terminal, the 1939 terminal, now named East Terminal, received another expansion and renovation completed in 1973. New ticket lobbies were built for American Airlines and United Airlines, the original portion was turned into a baggage claim area and jetways were added for the first time. An expansion and renovation of West Terminal was announced in 1977 and completed in 1982. Two gates were added, the front of the terminal received a two-story addition, new ceilings were installed, and the original blue exterior was repainted gray. This configuration of the airport remained for the next fifteen years.

A large Curtiss-Wright plant once existed at the Airport. In 1940, the company broke ground on the plant on the southeast side of the airport and dedicated it in August 1941. The building was sold to Westinghouse in 1946 after the end of World War II. Westinghouse sold the facility to Buffalo developer Paul Snyder in 1985, who attempted to repurpose the building as the Buffalo Airport Center industrial park. This was not successful and the building was shuttered in 1991. After sitting vacant for nearly a decade, the facility was demolished in 1999 to allow Runway 14/32 to be lengthened. In 2006 the main runway was repaved and extended 750 feet (230 m), its first major upgrade since 1980 and the secondary runway was extended 1,000 feet (300 m).

In 2008 some local residents attempted to petition to rename the airport to "Buffalo Tim Russert International Airport" after Buffalo native and Meet the Press moderator Tim Russert after his sudden death; the honor instead went to a stretch of Route 20A/Big Tree Road passing south of Highmark Stadium, the home of his beloved Bills.

Current terminal

In 1991 it was decided a new terminal would make more sense than continued renovations. Construction of the new building designed by the Greater Buffalo International Airport (GBIA) Design Group, a joint venture composed of Kohn Pederson Fox Associates, CannonDesign, and William Nicholas Bodouva began in 1995 in between the two existing terminals.

The new $56 million terminal (at newly named Buffalo-Niagara International Airport) opened on November 3, 1997, with 15 gates. The old terminals were demolished immediately to allow expansion. The new building was expanded in 2001, increasing the number of gates to 24. The entire terminal has a total floor area of 462,256 square feet (42,945.0 m2).

In late 2017 the terminal began an $80 million renovation and expansion with more than 54,000 square feet (5,000 m2) of new space as part of the airport's 2013 master plan. The expansion will create secure walkways on the east and west side of the terminal for arriving passengers and relocate the central exit walkway to eliminate bottlenecks with departing passengers on the second floor. This will also create expanded curbside space for arriving and departing passengers. The renovation will also replace the baggage claim area's three flat plate baggage carousels with four sloped plate carousels, doubling the current capacity. Preparations began in December 2018, and groundbreaking and major construction began in February 2019. The renovations were completed in 2021. As part of the master plan, this expansion allows for the creation of a new pier south of the current east concourse.