The company said the Operations, Maintenance and Defense of Army Communications in Southwest Asia and Central Asia contract could be worth $788 million if all options are exercised.
The contract, issued by the U.S. Army Contracting Command, features a phase-in period, a base period, two one-year options, and two one-year award terms.
Exelis has provided such services since 2005.
"Providing a multitude of critical IT services to our nation's warfighters is a vital discipline at Exelis," said Ken Hunzeker, president of the Exelis Mission Systems division.
"This contract award allows us to continue a long-standing tradition of exceptional IT and related services support to our military customers. It's a testament of customer confidence in Exelis performance and our position as a leader in managing and protecting critical networks around the world."