Jadzia's Starfleet career was often affected by her status as a joined Trill. As Curzon was also a Starfleet officer, Jadzia came to the job with more experience and knowledge than most officers twice her age. She remembers first hand what it is like to serve on a variety of different ships, and remembers the part Curzon played in some of the earliest peace negotiations with the Klingons. It is a difficult position, but she copes admirably. Shortly after arriving at the station Deep Space Nine, there are allegations of murder levelled against her previous host, Curzon Dax, by the son of the alleged victim. Jadzia's colleagues are obviously concerned that she was being asked to answer charges made against a man who they would consider had died some time before. They find it hard to understand why she was prepared to stand trial, and do everything they can to defend her until the charges were dropped.

Jadzia was a  brilliant young woman, who worked her way up through the ranks from ensign to commander, combined with the life experiences of seven others, including Curzon, a distinguished Starfleet ambassador. Shortly after her 'joining; Jadzia is assigned the position of science officer on Deep Space Nine. During that time, she is involved in some extraordinary adventures. Deep Space Nine is no exception, but the mixture of Federation personnel. Bajoran militia, such as Chief of Security Odo and Major Kira  Nerys, and freely operating agents such as the Cardassians and Ferengi, is not harmonious at first. It takes time for Jadzia to adjust to this assignment, her hard work soon win her admiration from all sides, especially for the part she plays in the discovery of the Bajoran wormhole. As her duty station in Ops is directly adjacent to Kira , the women soon became close friends. The rigorous fitness regime Jadzia follows using Klingon  callisthenics ensures she is in fine physical condition. Jadzia was a professional officer who knew not to let her relationship with, and subsequent marriage to, her colleague Worf affect her Starfleet duties.

 Jadzia forms part of the crew that breaks through Dominion ranks, and re-takes Deep Space Nine, a major turning point in the ongoing war. Jadzia returns to Deep Space Nine, but the war is far from over. One of her most dangerous missions was, when she accompanies her husband, Worf, on a mission to rescue a Cardassian double agent. Journeying to the jungles of the planet Soukara, the newly weds run into Jem'Hadar forces; although they manage to kill the patrol, Jadzia is shot, and badly injured. Her commitment to Starfleet is once again illustrated when she insists Worf continue with the mission, leaving her to suffer a certain death. As a Starfleet-officer Worf is compelled to carry out his mission, but but not this time, as a husband, he chooses instead to save the woman he loves.

Toward the end of 2374, Starfleet Command decides to take the offensive in the Dominion war. Sisko leads an invasion force to Cardassia, leaving Jadzia in charge of Deep Space Nine, with tragic consequences. When Gul Dukat decides to put his plan to drive the Prophets from the worm hole into action, he releases a Pah-wraith, and becomes possessed by its power. Dukat materializes in Deep Space Nine's Bajoran shrine, and fatally wounds Jadzia while she tries to protect a sacred Orb of the Prophets. Bashir is unable to save Jadzia's life, but the Dax symbiont does survive. Its association with Starfleet, and Deep Space Nine, is far from over. Jadzia's friends help the new Dax host, a young Starfleet counsellor named Ezri to understand her previous hosts. All of Jadzia's Starfleet experiences will be with Dax, ensuring that Jadzia will never be forgotten.