Police discovered the dead kangaroos on Commonwealth land in Singleton along with a box of ammunition and two cartridges on October 8.
On Friday morning, officers from the Hunter Valley Rural Crime Prevention Team, assisted by officers from the Port Stephens-Hunter division, raided a property in Williamtown.
During a search of the home, three firearms were allegedly discovered.
Police said several more firearms have since been seized at a second property in the Hunter region.
A 43-year-old man was arrested and taken to Raymond Terrace Police Station where he was charged with a string of offences.
The charges include, committing an act of aggravated cruelty on an animal, discharging a firearm in a Commonwealth area that is prohibited, trespassing onto Commonwealth land, not storing a firearm safely and harm or attempt to harm a protected animal.
A Firearms Suspension Notice has been issued.
The man was granted strict conditional bail to appear before Raymond Terrace Local Court on January 13.