Alliance Prime was the seat of power of the loosely allied Alliance worlds, and the meeting location for the Alliance Council. The Supreme Arbiter, Sarek of Vulcan, and Deputy Arbiter Koval both maintained officers on Alliance Prime.
In 2283, an apparently chance encounter between Guinan and Tal, then commander of the Cormier, led to her saving his life from shoddy repairs; this led to Tal accepting Guinan as a passenger and adviser on the ships he served on.
In 2292, the Cardassian councilman Zarcot stormed out and resigned his post, and set about undermining Sarek's power. One such tact included exaggerating the importance and danger of the Vortex, forcing Sarek to leave Alliance Prime aboard the Wisdom in 2293. While away, Sarek ordered that if any vessel were to approach Alliance Prime, to keep them in high orbit, out of transporter range.
The D'Zidran contacted Alliance Prime and requested that a fleet-wide alert be issued for sightings of the time traveling Montgomery Scott or the shuttlecraft Goddard, based on the suggestion of the USS Enterprise-D, which had followed them back in time.
After the Enterprise uncovered the Borg's utilization of the Narisians, the Borg killed all of the Narisians, including those on Alliance Prime which had been unknowingly providing them with secret intelligence. With the Borg aware of the Enterprise, they released a large fleet; Sarek ordered all available ships to intercept the fleet of Borg cubes, although he had the thought to instead tell the fleet to fall back to Alliance Prime or Vulcan. (Star Trek novel: Engines of Destiny)