In the years leading up to the Yinchorri Uprisng, Choi took Theen Fida as his Padawan. In 33 BBY, Choi volunteered to go to Yitheeth as part of a Jedi task force consisting of himself, Theen Fida, Adi Gallia and Eeth Koth. While on board a Consular-class cruiser, the four Jedi crash-landed on the oceanic world of Yitheeth—fortunately, both Choi and Fida were skilled swimmers. Once the Jedi had regrouped, they returned to their mission, which was to find the Yinchorri head quarters—however, after a skirmish with some Yinchorri warriors, they realized the HQ was not on the planet, and that they had walked into an enemy ambush.
Choi and the other Jedi managed to fight their way through the ambush and find transport off the planet. The four Jedi then traveled to the nearby planet of Yibikkoror, where Micah Giett, Plo Koon, Lilit Twoseas and her Padawan K'Kruhk were carrying out a similar mission as that of Tsui. The two groups of Jedi met, and set a course for Yinchorr, where Mace Windu, Qui-Gon Jinn, Obi-Wan Kenobi and Saesee Tiin were busy holding off a massive Yinchorri attack. Tsui and the other Jedi joined the fight, and during the ensuing battle, Theen Fida was killed by the Yinchorri. Tsui caught Holmar Grahrk trying to steal a Consular-class cruiser to escape Yinchorr, and discovered that Holmar was working in unison with his cousin, Vilmarh Grahrk. Choi later attended the funeral of his Padawan on Coruscant, who, along with Lilit Twoseas and Micah Giett, had died defending the Republic.
Tsui went on to become a General during the Clone Wars, leading Red Squadron into battle during the Defense of Kamino. The Jedi's battle plan assigned Tsui's squadron with the task of taking on the attacking Droid fighters, while Blue Squadron, under the command of Obi-Wan Kenobi, attacked incoming troop transports. During the battle, Master Kossex of Red Squadron was shot down and was killed instantly.
Later in the war, Master Choi was one of several Jedi who were on the Republic Troopship VCD987. While en route to the planet Drongar, VCD987 came under attack by an immensely superior Separatist force and sustained massive damage to its engines—with the engines no longer functioning, Separatist troops, under the leadership of Count Dooku, boarded the ship and cornered Tsui, Kai Justiss and Sian Jeisel. In an attempt to appear merciful and thus sway Jedi to the Separatist cause, Dooku allowed the captured Jedi to go free, instead choosing to only kill the clones which were aboard the ship instead.
During the Battle of Kashyyyk coordinated by Master Yoda, Tsui Choi and a team of Aleenan scouts performed reconnaissance missions riding can-cells through the wild terrains of the planet.
Tsui Choi survived Order 66, and managed to evade and kill his clone trooper commander, and a squad of clone troopers, on Eriadu during the first month of the Great Jedi Purge. He was eventually reunited with fellow Jedi survivor Bultar Swan, and engineered a rendezvous on Kessel with six other Jedi survivors. The other Jedi, particularly Koffi Arana, wanted to strike back at Palpatine and Darth Vader, but Tsui disagreed, refusing to go down the path which would lead to the dark side. However, Tsui was shocked to learn that Master Shadday Potkin had leaked information to Darth Vader that Obi-Wan Kenobi would be present at the Conclave. Tsui originally didn't want to fight Vader, but after Sian-Lan Wezz was killed, he told Bultar he had no other choice, and threw himself into the battle. During the ensuing fight, he managed to slice off Vader's robotic hand with his lightsaber. Despite losing his hand, Vader managed to kill Sia-Lan Wezz, Ma'kis'shaalas, Koffi Arana abd Shadday Potkin. Although many Jedi were lost, Tsui, along with Roblio Darte amd Jastus Farr, used the force to launch a barrage of boulders at the Dark Lord.
With Vader outmaneuvered and apparently outnumbered, Tsui was left with no choice but to strike down the fallen Jedi. However, before he could do so, Imperal stormtroopers arrived. Initially, Tsui was able to block their shots, and Roblio Darte shielded himself with a piece of rubble. Tsui leapt up to the balcony where the troopers were standing, but before he could cut them down, Vader used a force grip on him, holding him in mid-air. Tsui, knowing that he was close to death, launched one last attack against Vader by throwing his lightsaber at Vader, cutting a hole in his helmet. Immediately thereafter, Tsui was gunned down by the stormtroopers, and Vader released his Force Grip allowing the body to fall to the ground.
When the Galactic Empire emerged, "official" records compiled by Sate Pestage stated that Choi was executed for illegal spice trafficking.