Sergeant Major O'Bryant enlisted in the United States Marine Corps in June 2002 and reported to recruit training at Marine Corps Recruit Depot Parris Island, South Carolina, in March 2003. Upon graduation, he was meritoriously promoted to Private First Class and proceeded to Marine Combat Training, followed by the Field Radio Operators Course at Marine Corps Communication-Electronics School. Due to his outstanding performance and top academic standing, he was selected to attend the Multi-Channel Equipment Operator Course, which he completed in October 2003. He was subsequently assigned as a Multi-Channel Radio Operator with Company C, 8th Communication Battalion, II Marine Expeditionary Force (II MEF).
In February 2004, Lance Corporal O'Bryant deployed to Iraq in support of Operation Iraqi Freedom, where he served with Combat Service Support Group 11 as a Field Wireman, operating outside his military occupational specialty (MOS). Upon returning, he was reassigned within 8th Communication Battalion to Support Company and later deployed again in 2005, this time supporting the 2nd Marine Division as a TRC-170 Operator. During his second combat deployment, he was promoted to Corporal and served as Assistant TRC-170 Site Chief and Motor Transportation Noncommissioned Officer. Following his return, he continued to take on key leadership roles including Training NCO, Assistant Platoon Sergeant, and Assistant TRC-170 Chief, and was promoted to Sergeant.
In March 2007, Sergeant O'Bryant transitioned from active duty to the Selected Marine Corps Reserve (SMCR), where he was assigned to the Individual Mobilized Augmentee (IMA) Detachment, II MEF, serving as the Radio Chief. During this assignment, he contributed to the field testing and integration of the MRC-142C radio system across the Marine Corps. In 2011, he was promoted to Staff Sergeant and subsequently transferred to the Individual Ready Reserve.
Returning to the SMCR in 2012, Staff Sergeant O'Bryant joined Headquarters and Service Company, Combat Logistics Regiment 45 (CLR-45), where he assumed responsibilities as Platoon Commander. He played a key role in establishing the structure and capability of the newly aligned Communications Platoon during the regiment's activation. He ensured all Marines transitioning into the communications MOS successfully completed formal training and oversaw their development. In 2014, he was promoted to Gunnery Sergeant.
In April 2015, Gunnery Sergeant O'Bryant reported to Headquarters and Service Company, 1st Battalion, 23rd Marine Regiment, where he served as the Communications Chief. He was instrumental in designing and executing the communications infrastructure for multiple training evolutions, including the Integrated Training Exercise at Marine Corps Air Ground Combat Center Twentynine Palms, California. In 2018, he transferred to Communication Company, CLR-45, where he served as the Transmission Staff Noncommissioned Officer-in-Charge (SNCOIC). During this period, he led the company's participation in Exercise Northern Strike, a joint service training exercise, while also ensuring accountability for all Controlled Cryptographic Items.
Promoted to First Sergeant in July 2020, he assumed the role of Senior Enlisted Leader for Headquarters Battery, 2nd Battalion, 14th Marine Regiment. In January 2023, he transferred to Battery N, 5th Battalion, 14th Marine Regiment and mobilized as the unit's Senior Enlisted Leader. In this capacity, he supported artillery operations for Battalion Landing Team 2/1, the ground combat element of the 31st Marine Expeditionary Unit (MEU). While forward deployed with the 31st MEU, First Sergeant O'Bryant provided leadership during Exercise Talisman Sabre, a major biennial multinational training exercise conducted in Australia.
In January 2024, he was promoted to Sergeant Major and assumed his billet as the Senior Enlisted Leader of 4th Law Enforcement Battalion.
Sergeant Major O'Bryant's personal decorations include the Navy and Marine Corps Commendation Medal and Navy and Marine Corps Achievement Medal.