Once known as TZ-1719, Jannah is a human female who formerly served as a stormtrooper in the First Order, but now resides on Kef Bir after abandoning her post. This freedom fighter commanded a tribe of warriors on the ocean moon during the First Order-Resistance War. She would later become an important ally to the Resistance. Her weapon of choice was an energy bow. Finn expressed surprise upon hearing her story, having believed himself to be the only First Order defector until their meeting. During the Battle of Exegol, Jannah and her group were instrumental in the Resistance's efforts to defeat the Sith Eternal's fleet, known as the Final Order.
During the Battle of Ansett Island, Jannah and her squad of stormtroopers received orders to open fire on unarmed civilians. In defiance of these orders, Jannah and her unit refused, choosing instead to lay down their weapons. They then deserted the First Order, choosing self-imposed exile on Kef Bir, a moon orbiting Endor.
In 35 ABY, Rey, Finn, Poe Dameron, Chewbacca, BB-8, C-3PO, and D-O, all operatives of the Resistance, landed on Kef Bir in their quest to locate the Emperor's wayfinder. After Babu Frik informed Jannah about the Resistance's mission, she committed to assisting them. Jannah then assisted Finn and Dameron in repairing the heavily damaged Millennium Falcon. While working on the Falcon, Jannah gave Finn a component that he recognized as being of First Order origin. Upon realizing Finn's connection to the First Order, Jannah revealed that she and her entire company had once been stormtroopers who, like Finn during the Attack on Tuanul, had refused to fire on civilians. Jannah described it not as a conscious decision, but as a matter of instinct, to which Finn responded that it was likely the Force that had brought them together. Jannah was taken aback, surprised that Finn spoke of the Force as something real, to which he affirmed that it was. At that moment, BB-8 interrupted them to inform them that Rey was no longer with them. Leaving the Falcon, Finn realized with alarm that Rey had impatiently taken one of the sea skiffs and gone to the ruins of the second Death Star. Recognizing the danger, Jannah offered Finn another sea skiff to aid Rey. Aboard the sea skiff, Jannah and Finn navigated the wreckage's corridors in search of Rey. Hearing the sounds of clashing lightsabers, they rushed out to the trench and found her engaged in combat with Supreme Leader Kylo Ren. When Finn tried to intervene, he called out her name but was pushed back by the Force. As Finn attempted to interfere again, Jannah told him that they could not follow them.
Marooned on the ruins, Finn contacted Poe and requested a rescue. Jannah, alongside Company 77, boarded the Millennium Falcon and journeyed back to the Resistance base on Ajan Kloss, where they received the news of Leia's passing. Poe was subsequently appointed General of the Resistance. Shortly after, they learned that Kijimi had been completely destroyed by the Sith Eternal. Drawing on advice from Lando Calrissian and with Finn serving as his co-general, Poe formulated a strategy to eliminate the Xyston-class Star Destroyers of the Final Order. While Lando and Chewbacca utilized the Falcon to gather support from various free worlds, Jannah and her crew gathered their orbaks, boarded the Fortitude, and set course for Exegol, thanks to Rey's use of Kylo Ren's wayfinder to transmit the map to the Resistance.
Upon arriving at Exegol, the Resistance found themselves under immediate attack from the Sith Eternal forces. As the Exegol air team worked to protect the ground team, the fleet's navigation tower unexpectedly went offline. Realizing that disabling the tower was the only way to prevent the Sith Star Destroyers from escaping Exegol, the Resistance considered retreating. However, Finn sensed through the Force that the navigation signal originated from the Resurgent-class Star Destroyer Steadfast. When Jannah inquired how he knew, Finn simply attributed it to a "feeling." After landing on the ship's hull, Jannah, Finn, and the rest of the Resistance team rode across the ship on orbaks, facing off against Sith troopers. Jannah threw a detonator to distract the troopers, giving BB-8 enough time to open the hatch, during which she shot down a Sith Jetpack Trooper. Once BB-8 had opened the hatch, they dropped a bandolier of grenades, which destroyed the hatch and temporarily disabled the navigation signal.
As everyone retreated, Finn realized that the Sith Eternal intended to reboot the system. He decided to remain behind and destroy the Resurgent Star Destroyer, and Jannah chose to stay with him to assist. By turning one of the destroyer's turbolasers on its bridge, Jannah and Finn witnessed the arrival of a Citizens' Fleet from across the galaxy, led by Lando, which turned the tide of the battle. However, deep within the Sith Citadel, Darth Sidious, now fully revived by absorbing Rey and Ben Solo's Force dyad, unleashed a massive surge of Force lightning at the fleet, temporarily crippling them. Rey, guided by the spirits of past Jedi, wielded both the Skywalker lightsaber and Leia's lightsaber to defeat the Sith Lord. With Sidious's demise and the Force lightning ceasing, Jannah and Finn were able to use the turbolaser to destroy the command ship, killing Allegiant General Enric Pryde. The Steadfast began to plummet towards the surface with Jannah and Finn still aboard, but they were rescued by Lando and Chewbacca aboard the Millennium Falcon. With the Sith fleet destroyed and Sidious defeated, the Resistance and their civilian allies emerged victorious and retreated back to Ajan Kloss.
Upon their return to Ajan Kloss, the Resistance and their allies celebrated their triumph and the downfall of Sidious and the Sith Eternal. Jannah, seeing Lando, sat beside him and inquired about his origins, to which he responded, the Gold system. In turn, Lando asked Jannah about her home, but she confessed that she did not know. With a smile, Lando offered to assist Jannah in traversing the galaxy to locate her family.
Jannah was an extremely skilled engineer who fashioned her energy bow from salvaged blaster rifles. She also had a natural talent for inspiring trust and loyalty in those around her.
Naomi Ackie played Jannah in Star Wars: Episode IX The Rise of Skywalker in 2019, the concluding chapter of the Star Wars sequel trilogy. Jannah's name and image were initially revealed at the "Star Wars: Episode IX" panel during Celebration Chicago on April 12, 2019. Ackie underwent seven months of horseback riding training in preparation for her role.