The Negotiator was under the command of Admiral Block, where it was adorned with three red markings on each wing surface and wore the symbol of the Open Circle Fleet. Serving as the flagship of Obi-Wan Kenobi, it was most likely named after Obi-Wan's moniker, "The Negotiator".
During to the Battle of Christophsis, the Negotiator was sent to Christophsis to break Admiral Trench's blockade and rescue Senator Bail Organa and his troops. During this time, a prototype stealth ship was located in the main hangar.
Later on, Negotiator, the Resolute and another Venator-class cruiser battled against the Separatist warship of General Grievous, the Malevolence, which had dealt devastating losses to the Republic fleet in 22 BBY with its massive Ion cannon. The ship had already been crippled by the Y-wing starfighter squadron, Shadow Squadron, when the Republic cruisers arrived and aided in further damaging the ship. Though the cruisers were forced to call off their attack when Grievous captured Senator Padmé Amidala as a hostage in order for the burning warship to escape. But, Skywalker and Kenobi boarded the ship to save Amidala, and succeeded in sabotaging the navicomputer to send the Malevolence directly into a nearby moon.
In 20 BBY, Grievous launched a sneak attack on a task force which the Negotiator was a part of and severely damaged the ship. Kenobi and his men went down to the cruiser's hangar bay to confront Grievous and his droid boarding parties, but they were overpowered and, after only narrowly evading them, Kenobi ordered the Negotiator's crew to abandon ship. In order to prevent Grievous from accessing the ship's databanks and to leave a proper "parting gift", he activated the cruiser's self destruct before fleeing to an escape pod. Grievous only barely escaped the Negotiator aboard his shuttle before it was destroyed.