Like its predecessor, Justice, the ∞ Justice can dock with the powerful METEOR support system weapon platform, granting it powerful thrusters and an even more powerful armament of battleship-caliber beam cannons, large beam swords, and dozens of heavy missile launchers.

Following ZAFT's repair and use of the Requiem superweapon, the Three Ships Alliance, together with the Orb fleet and several defected Earth Alliance and ZAFT ships, launched an attack on Requiem's Station One, spearheaded by the METEOR-equipped Strike Freedom and ∞ Justice. Once the two mobile suits bypassed ZAFT's defense forces, they used their METEOR's beam swords to slice Station One in half, rendering it inoperable. Immediately afterward, the ∞ Justice took part in the Battle of Messiah, the final battle of the war, where Athrun single-handedly disabled both Lunamaria Hawke's ZGMF-X56S/α Force Impulse Gundam and Shinn Asuka's ZGMF-X42S Destiny Gundam, before utilizing the beam sabers and beam blades on the Fatum-01 to cripple the LHM-BB01 Minerva by ramming it to the ship's thrusters.