Under the direct command of Darth Vader, it was used as his flagship in the hunt for Admiral Harkov and his fleet. It participated in the attack on the Rebel space station DS 5 to apprehend Harkov. During the battle, the YT-1300 transport Geddawai and Delta-class DX-9 stormtrooper transport Kolermigon were captured and brought to the Garrett, and Harkov was interrogated and executed by Vader for his treachery.
While mopping up the remainder of Harkov's fleet in the Ottega system, the Garrett came under fire from forces under the command of Demetrius Zaarin. The attack force consisted of three groups of Assassin-class corvettes called Arditi, Falcon and BaKaar, Gamma-class ATR-6 assault transports and Assault Gunboats. However, Maarek Stele managed to fight off and destroy Zaarin's forces. Immediately after returning to the Garrett, Vader soon believed that Emperor Palpatine was in danger and he knew that he needed to get back to Coruscant. However, due to the damage the ship had sustained, Vader couldn't arrive in time, so he used TIE Defenders to try to reach Coruscant.
The Garrett was also used to receive high-ranking Rebel and Bothan prisoners on board the Dreadnaught-class heavy cruiser Dargon who were connected to the attack of a freighter that was carrying a supercomputer containing details for a new Death Star. The Garrett also attacked and captured the Bothan transports Botani.
Not long after Zaarin's unsuccessful attempt to kill Palpatine, Namuura Din, one of Zaarin's commanders, decided to defect to the Alliance and informed the Mon Calamari cruiser Link to warn the Rebel fleet of the trap that Palpatine had prepared for them and gave them a Missile Boat prototype Sealion. The Garrett, along with Lord Vader, was sent to capture Din's flagship, Victory-class Star Destroyer Zeplin. After successfully capturing Din and interrogating him, Vader sent the Garrett to find and capture the Link before their commander could relay Rebel Command. During the operation to capture the Link the Garrett pursued the Sealion that escaped the battle and tracked it to a Rebel station Enin'sd, where it was to be disassembled and studied. The Garrett returned to find the Link captured and the secret of Endor safe. Vader would then use the Garrett in an operation to recover or destroy the Sealion.