His career started with a posting to the 6th Battalion followed by being posted to the 3rd Battalion where he served several postings up to the rank of Sergeant. He deployed with the 3rd Battalion on OP WARDEN in 1999/2000 as a Section Commander, OP CITADEL in 2002 as a Reconnaissance Patrol Commander and OP ASTUTE in 2006 as a Platoon Sergeant.

In 2008, Warrant Officer Casey was posted to Australian Defence Force Academy as a Divisional Sergeant.

At the start of 2009 Warrant Officer Casey was then posted to the Parachute Training School as a Parachute Jump Instructor in the position of Warrant Officer Static Line instructing and organising all Parachute Static Line Courses within the Australian Defence Force.

In 2012, he was posted to the 7th Battalion, the Royal Australian Regiment where he held appointments of Company Sergeant Major of Admin, Charlie, Support Company, and he was the only Rifle Company Sergeant Major during the battalions eight month Operation Slipper deployment to Afghanistan. This culminated with him being awarded the Australia Day Medallion for his efforts.

In 2015 Warrant Officer Casey was posted to Royal Military College Duntroon as a Small Group Instructor and the Operations Warrant Officer.

In 2017 on promotion Warrant Officer Class One, he was appointed as the Regimental Sergeant Major of the 4th/3rd Battalion, the Royal New South Wales Regiment and he was selected to be the Regimental Sergeant Major of Battle Group Waratah. Warrant Officer Casey has also held appointments as the Depot Coy Sergeant Major at the School of Infantry. He has commenced his appointment as the Regimental Sergeant Major of 5th Battalion, the Royal Australian Regiment with effect 2021.

Warrant Officer Class One Casey is married to Megan who is a High School PDHPE Teacher. He has three children, Zara (15), Heath (12), and Eden (10). He is a keen Rugby Union and League supporter, enjoys exercising and doing outdoor activities with his family.