The design of the RX-78-7 7th Gundam received feedback from the FSWS Plan. As such, it was designed from the ground up to equip Full Armor optional parts, namely the FA-78-3 and the HFA-78-3 options, and has mount latches for optional parts all over its body. It has a higher generator output than Gundam Units 1-6, which, coupled with sub-generators within the armor parts, allow it to operate with no loss in power even when equipped with Full Armor options. It is equipped with a number of advanced features, including magnet coating and a prototype panoramic monitor (though this was replaced with a standard cockpit in U.C. 0081). Its performance is roughly on par with the RX-78NT-1 Gundam NT-1.
The RX-78-7 was still in the design phase when the One Year War ended, and only the design of the frame was complete. After the war, work on the Gundam continued at Augusta Base, where it was tested by Lieutenant Cherie Allison. In truth, however, Cherie Allison was actually Tatiana Doerr, a member of the Zeon Remnants group Invisible Knights. Though she performed her duty as test pilot faithfully, she also secretly sent intelligence on the base, including the Gundam's data, back to Zeon.