Zero becomes Ultimate Zero when he wears the Ultimate Aegis, given to him by Ultraman Noa. This form gives Zero chest armor and a sword on his right arm in addition to more power and the ability to freely travel between universes.
Understanding the purpose of the Shield of Baradhi, Nao informs everyone not to lose hope and eventually, Zero is revived by Ultraman Noa, who bestows the Shield of Baradhi onto Zero, transforming the Ultra into Ultimate Zero. The other giants distract Belial to provide Zero enough time to charge his attack and killed Belial for good. With his mission over, Zero left a fully healed Run and formed the "Ultimate Force Zero".
Final Ultimate Zero is the Ultimate Aegis' final attack has it take the form of a bow with strings made of energy, when Zero pulls it, the construct charges with massive amounts of energy. Used to defeat Arch Belial. However, this attack exhausts Zero greatly. There is also another uncharged variant where the crossbow returns to the user instead and was used against Etelgar. This attack closely resembles Ultraman Nexus Junis Blue's Over Arrow-Ray Schtrom.