Sergeant Major O'Grady enlisted in April 2006 and completed recruit training at Marine Corps Recruit Depot, San Diego, California. After finishing entry-level training at the School of Infantry-West, he was assigned the military occupational specialty of 0311, Rifleman. In November 2006, Lance Corporal O'Grady reported to 1st Battalion, 4th Marines, Camp Pendleton, California. He deployed in support of Operation Iraqi Freedom in April 2007, and upon redeployment in August 2008, he was promoted to Corporal. Corporal O'Grady deployed again in October 2008 in support of Operation Iraqi Freedom. During his time with the battalion, he served as a grenadier, team leader, and squad leader.
In January 2010, he was promoted to Sergeant and executed a lateral move to the military occupational specialty of 6092, Aircraft Intermediate Level Structures Mechanic. He was assigned to Marine Aviation Logistics Squadron 39 at Camp Pendleton, California, where he was assigned to the Airframes Division and worked in the metal shop and the welding shop.
In September 2011, he reported to the Advisor Training Cell, I MEF, Camp Pendleton, California. In January 2012, he deployed in support of Operation Enduring Freedom as a military advisor at Camp Leatherneck, Joint Sustainment Academy Southwest. Upon redeployment in December 2012, he was assigned to the Advanced Composite shop.
In October 2013, he attended the Basic Recruiters Course in San Diego, California, and was assigned to Recruiting Station Orange, Recruiting Substation Pearl City, and Permanent Contact Station Hilo, Hawaii. He served as a production recruiter, and in December 2014, he was promoted to Staff Sergeant.
In February 2017, Staff Sergeant O'Grady reported to Marine Aviation Logistics Squadron 24 at Kaneohe Bay, Hawaii, where he served as a Non-Destructive Inspection Technician and the Airframes Branch Staff Noncommissioned Officer in Charge. In February 2018, he was promoted to Gunnery Sergeant, and in May 2018, he deployed to Okinawa, Japan, in support of the 31st Marine Expeditionary Unit. During this deployment, he was assigned to the USS WASP and conducted Humanitarian Assistance Disaster Relief operations.
In March 2020, Gunnery Sergeant O'Grady reported to Marine Aviation Logistics Squadron 41 at Naval Air Station Joint Reserve Base Fort Worth, Texas, where he served as the Quality Assurance Chief. In February 2022, he was promoted to the rank of First Sergeant and received orders to Combat Logistics Battalion 7. During his time at CLB-7 he served as the Company First Sergeant for Headquarters and Service Company and Motor Transportation Company.
In March 2024, First Sergeant O'Grady reported to Sergeant's School, Staff Noncommissioned Officers Academy, Twentynine Palms, California, to assume the duties as Director. In June 2025, Sergeant Major O'Grady was frocked to his current rank and directed to report to Marine Air Support Squadron 2 to serve as the Squadron Sergeant Major.
His personal awards include the Meritorious Service Medal, Navy/Marine Corps Commendation Medal with 2 gold stars, and the Navy/Marine Corps Achievement Medal with 1 gold star.