ax made his first chronological appearance in Mortal Kombat II, though, in terms of the storyline, his first adventure is depicted in Mortal Kombat: Special Forces. This game opened depicting a prison break at Special Forces' detention facility. Jax, driving along a highway, received a transmission from his fellow Special Forces operative Gemini detailing the escape and the escapees: No Face, Tasia, Jarek and Tremor. She informed him that they had escaped to a warehouse on the town's south side, likely receiving assistance from an outside source. Jax surmised that source to be Kano. He received another transmission from one Lieutenant Sanchez, whose squad had arrived at the warehouse. After the transmission was cut off at the source, Jax arrived at the scene to find the squad destroyed. For this, he swore he would achieve vengeance against Kano. Using prototype bionic implants on his arms in order to enhance his strength, Jax set out to find his enemy.

Infiltrating the warehouse, Jax confronted No-Face and dispatched him. Proceeding into the sewers, he did likewise to Tasia. At this point, Gemini contacted Jax again and informed him that the Black Dragon were using a corporate building as a front for their base of operations. At the building, Jax confronted and defeated Jarek. His investigation then led him to the town of the lost city of Sin Kiang. There, he defeated Tremor and discovered a portal to Outworld. Surmising that the portal was linked to Kano's plans of global domination, he entered. Jax caught up with Kano, who had acquired an artifact called the Eye of Shitian. Through this artifact, Kano could acquire great power. After an exchange of words, the two fought and Jax emerged the victor. He used the Eye's power to bring them both back to Earthrealm and brought Kano into custody, only to have the criminal escape at a later date. At this point, Jax ceased using his bionic implants.

Jax's first appearance on a fighting game was in Mortal Kombat II. Jax first came across the Earthrealm warriors when he found Johnny Cage in the waters close to the Special Forces Agency. Jax began interrogating him. Cage explains his story and although is not trusted at first, is eventually set free. Jax doesn't believe the story of Johnny Cage until he receives a video signal from Sonya, whom is temporarily working with Kano to escape the Outworld. As an apology for Jax not believing Cage, he visits him at a commercial shoot where Johnny is being attacked. Jax participates in a short battle with Kintaro here. The battle is interrupted when the Earthrealm warriors arrive to help. After they save Johnny from the intruders, they travel into Outworld to compete in the tournament and save Sonya. Soon Jax came to learn of the Emperor's dark plans for Earthrealm. As soon as he had freed Sonya (and inadvertently Kano), he headed back home to warn his government of the impending danger. He would find himself frustrated, however, as not only did Kano escape back into Outworld, but the government did not believe the major.

Jax began to prepare for war covertly and once more outfitted his arms with bionic implants. After helping foil Shao Kahn's attempt to permanently claim Earth as his own, Jax became the commanding officer of the Outer World Investigation Agency (OIA). They operated from an underground bunker and had scouts in various realms. Not only did they explore and map these realms, but they also looked for and destroyed inter-realm portals that could lead to Earth.

He briefly assisted Raiden in the defeat of Shinnok after he found out that Sonya was in Edenia. It was during these events that both he and Sonya would find the Lin Kuei cyborg Cyrax, malfunctioning and trapped in a desert. Returning with him to their home base, they reversed the automation process, restored his humanity, and gained a new ally.

Years later, trouble would occur again. Not only were his agents Kenshi and Cyrax lost in Outworld, but the OIA underground facility was nuked into oblivion by the traitor Hsu Hao. When, soon after, Raiden summoned the Earthrealm warriors to the abandoned island of Shang Tsung and asked them to travel with him to Outworld to bring down the Deadly Alliance, Jax didn't hesitate. He used this trip as a cover to track down Hsu Hao and kill him by tearing out his artificial heart.

During the final attack on the Deadly Alliance, Jax along with the other Earthrealm warriors were killed (He, Sonya and Johnny Cage were overwhelmed by the Deadly Alliance's Tarkartan warriors). After Onaga defeated Raiden and the Deadly Alliance, he resurrected Jax and his Earthrealm friends as his slaves. Jax returns in Mortal Kombat: Unchained, and it is revealed that Jax is saved, thanks to the efforts of Ermac and the spirit of Liu Kang, as shown in Ermac's Deception ending. Jax also returned in Mortal Kombat: Armageddon.

In his ending for Unchained, he brutally pounded Onaga senseless (Shujinko failed despite absorbing Jax's fighting styles but lacking the raw anger needed) his strength propelled by unexplained rage. As an encore, he embedded the Netherrealm Kamidogu in the Dragon King's head.

Sonya's Mortal Kombat:Armageddon biography briefly mentions Jax as being part of a search team deployed by her to search for survivors after destroying a Tekunin warship. Jax disappears afterwards, with Sonya assuming that he had been captured, noting that his arms' bioscanners were giving her strange readings about his health before winking out entirely. In his ending for Mortal Kombat: Armageddon, Jax becomes a full cyborg after defeating Blaze, and leaves the Special Forces. He then takes control of the Tekunin by defeating Sektor, an apparent act of revenge after discovering a neural control chip implanted in his brain by the Tekunin leader. The ending also states that, after this, it is unknown if Jax would ever return to the Special Forces