The company provides services in various sectors including cybersecurity, intelligence, defense, transportation, environmental remediation, and urban development.

[19] Parsons interest in bridge projects grew through the 1980s, 1990s, and 2000s leveraging credentials enabled by acquisition of firms including DeLeuw, Cather, and Company in 1977[20] and Steinman, Boynton, Gronquist and Birdsall (SBGB) in 1988.

[30] In April 1996, Parsons CEO at the time, Leonard Pieroni, was killed in a U.S. Air Force plane crash in the Balkans along with U.S. Commerce Secretary Ron Brown.

[32] In 2012, Parsons developed the logistics strategy for movement of the Space Shuttle Endeavour from Los Angeles International Airport to the California Science Center near downtown.

[37] On September 1, 2023, Parsons announced the move of its headquarters to Chantilly, VA.[1] Discussing the company's business outlook in February 2024, CEO Carey Smith stated that the company believes it will continue to see strong demand for its solutions, including cyber, electronic warfare, signals collection, space, missile defense and critical Infrastructure protection given world-wide geopolitical outlook.

[38][39] 1940s Less than 2 months after Parsons was founded, they were hired to provide turnkey engineering, management, and oil well drilling services to the great divide in Colorado, United States.

[41] 1950s In 1952, the U.S. Army awarded Parsons a multi-year design and construction contract role for numerous laboratory and test facilities at the Redstone Arsenal in Huntsville, Alabama.

[45][46] In 1958, Parsons began fabrication of electronics and instrumentation including miss-distance indicators for the Pershing Medium Range Ballistic Missile.

[47] In June 1959, Parsons was awarded a contract for Titan ICBM facility design to be constructed near Moses Lake Washington.

[48] 1960s In 1961, Parsons designed the installation plans for each of the 1,000 Minuteman intercontinental ballistic missiles, which were used by the U.S. Air Force during the Cold War.

[52] In February 1963, Parsons was contracted to design the Apollo Spacecraft Propulsion System Development Facility at White Sands New Mexico.

[53] In 1964, Parsons created a technical and economic blueprint for the North American Water and Power Alliance (NAWAPA), specifically in the United States, Canada and Mexico.

The plan outlined concepts to build an integrated system of dams, channels, tunnels, reservoirs, hydroelectric plants, and pumping stations.

The company provided the master plan, design, and construction management services for this self-contained industrial city of more that 100,000 people that produces oil, gas, and petrochemical products used worldwide.

[64] Continuing work in the middle east, Parsons won a contract to design, engineer, and manage the construction of multiple facilities for ARAMCO's Saudi Arabian gas program.

[65] In October 1976, the Federal Railroad Administration awarded Parsons, as part of a joint venture, the Northeast Corridor Improvement Program contract, which was to provide a 456-mile, high-speed rail service between Boston, New York, and Washington, D.C.[66] In 1977, Parsons completed a 4-year design-build turnkey program to build the Jeddah Airport in Saudi Arabia (also known as the King Abdulaziz International Airport).

[71] In 1985, the Los Angeles Metropolitan Transportation Authority hired a Parsons joint venture to provide commuter rail services and construction management of what would become the MTA's Red Line.

[74] In 1986, Parsons designed, engineered, and managed construction of the Red Dog mine air and sea ports along with the entire complex.

[75] In 1987, Parsons engineered, designed and delivered the Titan solid booster rocket test stand at Edwards Air Force Base in California.

[24] 1990s In 1992, the Port of Los Angeles selected Parsons to design the Pier 300 $60 million dry bulk terminal for international commodities such as coal and petroleum coke.

[91] 2000s On September 19, 2002, Parsons was awarded a contract to design, build commission and operate the Savannah River Salt Waste Processing Facility (SWPF) in South Carolina by the department of energy.

[93] On October 8, 2002, Parsons proceeded on the Tacoma Narrows Bridge, a design-build project, originally scheduled to be constructed in 55 months.

[95] In June 2003, a joint-venture team led by Bechtel National, Inc. and Parsons Corporation was selected to destroy chemical weapons at the Bluegrass Army Depot in Kentucky.

[109] In 2013, Parsons designed and managed construction for the earthworks, roads and water and wastewater in Saadiyat Island, Abu Dhabi, UAE.

[110] In October 2014, Parsons was awarded a contract by Tecon Investments to oversee major elements of the Dubai Design District (D3).

[116][117] In December 2019, it was announced that Parsons and Leidos Holdings Inc. had earned spots on a $4 billion contract to support the cleanup of a former nuclear weapons site in southern Washington state.

The contract calls for production and delivery of armored vehicles equipped to clear mines or unexploded ordnance from airfields using three-kilowatt ZEUS laser weapon.

[122] In June 2022, the Defense Health Agency awarded Parsons a spot on a potential $10 billion multi-award contract for military medical research and development support.

[123] In 2023, Parsons was confirmed as the delivery partner for The Line at NEOM, a 170 km linear city being built in Saudi Arabia.

[126] In April 2024, Parsons secured a position on a $464 million contract with the United States Army Environmental Command (USAEC) for services involving hazardous waste, including perfluoroalkyl and polyfluoroalkyl substances (PFAS).