Cooker was born and bred on Kamino. He was assigned to Green Company, in the 41st Elite Corps as a sniper. He then participated in the Clone Wars in 22 BBY.
During the war, Cooker was know for being able to cause Battle Droid to combust by hitting them in their power cells, earning him the nickname "Cooker".
In 21 BBY, Cooker fought in the Battle of Rishii, under command of Jedi General Kitt Fisto, where the CIS held control of the planet Rishii. The planet's chieftain ordered Cooker and Green Company to take out the droids in the mines that were on the planet. The attack failed, and they were forced to fall back. Cooker was chosen by his commander to take out the Geonosians.