The all-cash transaction is valued at $4.7bn or $58 per share and inclusive of net debt.
The deal, which is scheduled to close next year, will be funded via existing cash and issuance of new debt.
The next steps now involve obtaining all the required clearances, regulatory approvals and associated customary closing conditions.
It marks the second acquisition announced by L3Harris this year and is expected to strengthen company’s existing defence industrial base.
The company will be able to drive its scientific discovery efforts by making specific investments in hypersonic and advanced missile technologies.
L3Harris CEO and chair Christopher Kubasik said: “With this acquisition, we will use the combined talents of more than 50,000 employees to drive continuous process improvement, enhance business operations and elevate performance of this crucial national asset.”
Headquartered in El Segundo, California, Aerojet Rocketdyne specialises in propulsion systems and energetics manufacturing for the defence, civil and commercial customers, including the US Department of Defense and NASA.
The company’s current annual revenue is estimated to be nearly $2.3bn.
Aerojet has different advanced manufacturing facilities across the US, including West Palm Beach and Orlando in Florida; Orange, Virginia; Canoga Park, California, among others.
Aerojet Rocketdyne CEO and president Eileen Drake said: “This agreement will accelerate innovation for national security propulsion solutions while providing a premium cash value for our shareholders and tremendous benefits for our employees, customers, partners and communities in which we operate.
“As part of L3Harris, we will bring our advanced technologies together with their substantial expertise and resources to accelerate our shared purpose: enabling defence of our nation and space exploration.”