Justyn Ma'Ning was a Jedi Master of the Jedi Order, a Human male who operated during the declining years of the Galactic Republic. Known for his involvement in the Outbound Flight Project, Ma'Ning, a middle-aged and balding man with a resonant voice, served under Master Jorus C'baoth, a figure with whom he frequently disagreed, and was tasked with overseeing the Jedi on board Dreadnaught-Four. During his time on Outbound Flight, Master Ma'Ning met his end at the hands of starfighters dispatched by order of Chiss Captain Mitth'raw'nuruodo.
Endowed with Force-sensitive abilities, Justyn Ma'Ning, a Human, underwent training in the ways of the Force under the guidance of the Jedi Order. Having achieved the rank of Jedi Master, Ma'Ning was among the five Jedi Masters chosen to accompany Master Jorus C'baoth on Outbound Flight as part of the Outbound Flight Project. This ambitious endeavor aimed to transport a large group of Jedi and colonists aboard a massive colony ship to the fringes of the galaxy and beyond, with the goal of documenting new discoveries and, hopefully, locating the missing Jedi Vergere.
Assigned command of Dreadnaught-Four, Master Ma'Ning outwardly showed support for Master C'baoth's directives, even as he questioned the necessity for the Jedi to amass greater power over the non-Jedi colonists on board. As C'baoth began separating families based on their connection to the Force, Master Ma'Ning grew increasingly worried about the obsessive man. Nevertheless, recognizing the critical shortage of Jedi peacekeeping forces during those perilous times, Master Ma'Ning conceded that the Jedi needed to maintain and expand their numbers by training new recruits. Ma'Ning only confided his concerns to Jedi Knight Lorana Jinzler, who pledged to discuss them with her master. However, Ma'Ning eventually confronted C'baoth directly. Accusing C'baoth of behaving more like a ruler than a wise sage, Master Ma'Ning's accusations were met with disbelief. Consequently, Ma'Ning initiated a Judgment Circle against C'baoth, scheduled to take place as soon as an immediate threat had been addressed.
As Ma'Ning was taking steps to relieve C'baoth of his command, Outbound Flight came under attack by a Chiss task force led by Force Commander Mitth'raw'nuruodo (whose core-named was "Thrawn"). The Jedi, unable to convene the Judgment Circle, hurried to their battle stations. However, they were severely outmatched by the Chiss's precision. During the initial assault, Master Ma'Ning was caught in an explosion and trapped beneath the molten bulkhead. As he lay dying, Ma'Ning summoned Jedi Knight Jinzler to his side and warned her that C'baoth had succumbed to the dark side of the Force. Urging Jinzler to gather as many passengers as possible and head to the massive ship's central core, he predicted that they would have the greatest chance of survival there. With his final breath, Master Ma'Ning reminded Jinzler of her duty as a Jedi to serve others, before succumbing to his injuries and becoming one with the Force.