Sergeant Major Gregory Walker enlisted in the Marine Corps from Recruiting Station Winston-Salem, North Carolina, on the 6th of January 1999 and attended Recruit Training at Marine Corps Recruit Depot (MCRD) Paris Island, South Carolina. Soon after, he reported for training at Marine Combat Training at (MCT) Camp Geiger, North Carolina. Upon completion of MCT, Sergeant Major Walker received orders to the Center for Naval Aviation Technical Training Marine Unit Camp Pendleton, California where he earned the MOS 6114, Light Attack Helicopter Mechanic.
In August of 1999, Sergeant Major Walker reported to Marine Light Attack Helicopter Squadron 773 (HMLA-773), 42nd Marine Aircraft Group (MAG-42), 4th Marine Air Wing (4th MAW), Naval Air Station Atlanta, Georgia. While attached to HMLA-773, Sergeant Major Walker participated in several Combined Arms Exercises, Joint Task Force operations, and participated in the NATO exercise Operation Battle Griffin in Vearnes, Norway.
In October 2002, Sergeant Major Walker received orders to HMLA-167, MAG-26, 2nd MAW, Marine Corps Air Station (MCAS) New River, North Carolina to holding qualifications as a Dual Plane Captain, Collateral Duty Inspector, and Collateral Duty Quality Assurance Representative.
From July 2003 to October 2004, Sergeant Major Walker was attached to Medium Lift Helicopter Squadron 266 Reinforced [HMM-266 (REIN)], 22nd Marine Expeditionary Unit (MEU) and deployed in support of Operation Enduring Freedom (OEF), Kandahar, Afghanistan.
From May 2005 to December 2005, Sergeant Major Walker was attached to HMM-261 (REIN), 22nd MEU. He performed the duties of Staff Non-Commissioned Officer-In-Charge (SNCOIC) for day crew maintenance.
From January 2005 to December 2008, Sergeant Major Walker went on to deploy with HMLA-167 in support of Operation Iraqi Freedom (OIF) 5-7 and OIF 7-9.2. During this period Sergeant Major Walker performed the duties of Aircraft Phase Supervisor and Aircraft Phase Coordinator.
From January of 2009 to January 2012, Sergeant Major Walker executed orders to Marine Corps Recruit Depot, San Diego, California and was assigned to Company K, 3rd Recruit Training Battalion. During his tour, Sergeant Major Walker completed eight cycles holding the billets of Drill Instructor, Experienced Drill Instructor, Senior Drill Instructor, and Chief Drill Instructor.
From January 2012 to April 2016, Sergeant Major Walker was attached to HMLA-469, MAG-39, 3rd MAW, MCAS Camp Pendleton, California. During his time at HMLA-469, Sergeant Major Walker deployed in support of OEF, Camp Bastion Afghanistan as a Quality Assurance Representative and in support of the Unit Deployment Program 15.1 to MCAS Futenma, Okinawa Japan as the Flight Line Division Chief.
In April 2016 Sergeant Major Walker reported to HMLA-269, MAG-26, 2nd MAW, MCAS New River, North Carolina. By August 2016, Sergeant Major Walker earned his Safe-For-Flight certification and was assigned to Marine Medium Tiltrotor Squadron 365 (REIN) in support of the 24th MEU where he held the billet of HMLA Detachment SNCOIC and Maintenance Controller.
On 1 January 2017, Sergeant Major Walker was promoted to the rank of First Sergeant and was attached to Company A, 2nd Combat Engineering Battalion, 2d Marine Division, Camp Lejeune, North Carolina. From February 2017 to May 2019, Sergeant Major Walker participated in several company and battalion field exercises (FEX), cold weather training at Fort Drum, New York, and a 2nd Marine Division FEX.
From May 2019 to September 2020, Sergeant Major Walker was attached to The Basic School, Quantico, Virginia. Sergeant Major Walker was assigned Company First Sergeant for Basic Officers Company F (6-19), Basic Officers Company C (3-20) and the Marines Awaiting Training Company M.
On 1 September 2021 Sergeant Major Walker was promoted to his current rank and received orders to Camp Lejeune, North Carolina, where he is assigned as the Battalion Sergeant Major at Combat Logistics Battalion 22, Combat Logistics Regiment 2, 2nd Marine Logistics Group. His personal decorations include the Meritorious Service Medal, Navy and Marine Corps Commendation Medal (gold star in lieu of second award) and the Navy and Marine Corps Achievement Medal.