The company was formed from the merger of L3 Technologies and Harris Corporation on June 29, 2019,[3] which made it the sixth-largest defense contractor in the United States.

In 1967, they merged with Radiation, Inc. of Melbourne, Florida, a developer of antenna, integrated circuit, and modem technology used in the space race.

[9] L-3 Communications was formed in 1997 to acquire certain business units from Lockheed Martin that had previously been part of Loral Corporation.

[13] Between 1999 and August 2021, L3Harris and predecessors spent $131.9 million lobbying for ICE radio procurement ($20,000),[14] the Intelligence Authorization Act ($​1,510,000),[15] DHS fund appropriations for unmanned vehicles ($430,000),[16] and night vision systems research ($20,000).

[17][18] In 2008, 72 Iraqi civilians sued L3 Services and CACI for human rights violations including "torture; cruel, inhuman, or degrading treatment; war crimes; assault and battery; sexual assault and battery; intentional infliction of emotional distress; negligent hiring and supervision; and negligent infliction of emotional distress."

A settlement was reached on October 10, 2012, which was the "first positive resolution to a U.S. civil case challenging detainee treatment outside the United States in the larger 'war on terror' context".

[19] In 2012, L3 subsidiary KDI Precision Products participated in the sale of 11,500 JDAM bomb fuzes to Israel, part of a $647 million contract deal.

Services and equipment help support surveillance and reconnaissance with autonomous surface vehicle, monitering, signal & control systems.

The initiative and prototype combine commercial technology to provide the United States military with collaborative autonomy when operating swarms of unmanned aircraft, ground vehicles, and marine seacraft.

[1] Headquartered in Palm Bay, Florida, Aerojet Rocketdyne consists of two sectors: "Missile Solutions" and "Space Propulsion and Power Systems".