Christopher R. O'Bryant enlisted in the Marine Corps in June 2002 and attended recruit training at MCRD Parris Island, SC in March 2003. After completion of basic training, he was meritoriously promoted to Private First Class and attended Marine Combat Training in June 2003. Once completed, Private First Class O'Bryant was directed to the Marine Corps Communication-Electronics School, where he attended Field Radio Operators Course in July 2003. Due to Private First Class O'Bryant's high class ranking, he was chosen and attended Multi-Channel Equipment Operator Course in October 2003. Upon completion, Lance Corporal O'Bryant was assigned to Company C, 8th Communication Battalion, II Marine Expeditionary Force as a Multi-Channel Radio Operator.

In 2004, while serving with 8th Communication Battalion, Lance Corporal O'Bryant was deployed to Iraq and temporarily assigned to Combat Service Support Group 11 in support of Operation Iraqi Freedom, serving outside of his MOS as a Field Wireman. Lance Corporal O'Bryant returned to 8th Communication Battalion and was assigned to Support Company, but in 2005, was again deployed to Iraq and temporarily assigned to 2d Marine Division in support of Operation Iraqi Freedom as a TRC-170 operator. During his second tour, Lance Corporal O'Bryant was promoted to Corporal and took on additional responsibilities as the Assistant TRC-170 Site Chief and Motor Transportation NCO. After completing his tour, Corporal O'Bryant returned to 8th Communication Battalion where he served as the Training NCO, Assistant Platoon Sergeant, and Assistant TRC-170 Chief and was promoted to Sergeant.

Sergeant O'Bryant left active duty in March 2007 and joined the Selected Marine Corps Reserves where he was assigned to the Individual Mobilized Augmentee Detachment, II Marine Expeditionary Force as the Radio Chief. During his time with the Individual Mobilized Augmentee Detachment, Sgt O'Bryant was part of a team of Marines that were responsible for field testing the MRC-142C during its introduction into the Marine Corps. In 2011, Sergeant O'Bryant was promoted to the rank of Staff Sergeant. In 2011, Staff Sergeant O'Bryant transferred to the Individual Ready Reserve.

In 2012 Staff Sergeant O'Bryant returned to the Selected Marine Corps Reserves where he was assigned to Headquarters and Service Company, Combat Logistics Regiment 45 as the Platoon Commander. Staff Sergeant O'Bryant was responsible for developing and implementing the organizational structure of the Communication Platoon during the activation of Combat Logistics Regiment 45, which was recently realigned to add communication occupational specialties. Staff Sergeant O'Bryant coordinated the conversion of all Marines that recently made a lateral move in communications and ensured all Marines attended their formal schools. Staff Sergeant O'Bryant served as the Assistant Communication Chief and in 2014 was promoted to the rank of Gunnery Sergeant.

In 2015, Gunnery Sergeant O'Bryant transferred to Headquarters and Service Company 1st Battalion 23d Marine Regiment as the Communication Chief. During his tenure, he assisted in the coordination and establishment of the communication architecture for two annual training events including the Integrated Training Exercise in 29 Palms, CA.

In 2018, Gunnery Sergeant O'Bryant transferred to Communication Company, Combat Logistics Regiment 45 as the Transmissions SNCOIC. Gunnery Sergeant served as the senior representative of Communication Company during Northern Strike, a joint service exercise and was responsible for maintaining accountability all the Communication Company's Controlled Cryptographic Items.

In July 2020, First Sergeant O'Bryant was promoted to his current rank and was assigned to Headquarters Battery, 2d Battalion 14th Marine Regiment.  In January 2023 he received order to 5th Battalion, 14th Marines, where he is currently serving as the Battery First Sergeant for Battery N.