The award is valued at $134 million and takes the U.S.-Britain production program to October 2013 and a total of 1,071 guns.
"Bringing M777 to the IBCT's will enhance their ability to carry out an ever-expanding range of missions," said Mike Smith, managing director of BAE Systems' Global Combat Systems Weapons business.
"This latest order reinforces the system's credentials while continuous development of subsystem enhancements underlines our determination to keep M777 the howitzer of choice."
Weighing less than 49,259 pounds, the M777 is the world's first artillery weapon to make widespread use of titanium and aluminum alloys, resulting in a howitzer that is half the weight of conventional towed 155mm systems.
As a result, it can be deployed by medium-lift helicopters quickly and beyond the reach of roadside bombs to otherwise inaccessible areas.
BAE Systems' facility at Hattiesburg, Miss., is responsible for final integration and testing of the weapon system.