First Sergeant Grainger is a native of Miami, Florida, and enlisted in the Marine Corps in June of 2005. He completed recruit training in June of 2005 at Marine Corps Recruit Depot, Parris Island, South Carolina where he was meritoriously promoted to PFC. In September 2005 PFC Grainger reported to Camp Geiger for Marine Combat Training. Upon completion, PFC Grainger was assigned to Naval Air Station Pensacola, and follow-on training at Marine Corps Air Station Cherry Point for training as an Aviation Ordnance Technician. He was promoted to the rank of Lance Corporal in February 2006.
In March 2006, LCpl Grainger received orders to Marine Corps Air Station Kaneohe Bay, Hawaii. During his tour he served as an Aviation Ordnance and Ammunition Technician at Headquarters Battalion. In November of 2006 he was promoted to the rank of Corporal. In September 2009 Corporal Grainger transferred to the Marine Corps Reserve, joining 4th Air Naval Gunfire Liaison Company (ANGLICO). In October 2010 he was promoted to the rank of Sergeant.
While at 4th ANGLICO Sergeant Grainger conducted a lateral move to the occupational specialty of Automotive Maintenance Technician and checked into Marine Corps Base Camp Lejeune to attend training. While outside of the active-duty ranks, Kyle Grainger started his civilian career as a Firefighter in Miami, Florida, attending Emergency Medical Technician Paramedic and Firefighting Schools. In May 2014, he was selected to Staff Sergeant and earned the position of the Motor Transport Maintenance Chief. In January 2016, Staff Sergeant Grainger attended the Marine Corps Advisor Course at Fort Story, Virginia. In April 2016 Staff Sergeant Grainger deployed to Jordan as the logistics advisor with Security Cooperation Training Team- Jordan.
In July of 2018, SSgt Grainger reported to Marine Corps Forces, South, Miami, Florida. While at MARFORSOUTH he served in the IMA as the Training Chief and Command Operations Center Watch Officer. In April of 2021 Staff Sergeant Grainger was promoted to Gunnery Sergeant. Gunnery Sergeant Grainger continued his assignments at MARFORSOUTH as Current Operations Chief, and Exercises Chief. Upon deactivating from ADOS with MARFORSOUTH, Kyle Grainger returned to his current civilian position at U.S. Southern Command at a Global Force Manager as a DOD civilian. In 2024 Gunnery Sergeant was promoted to his current rank of First Sergeant and assignment at Alpha Company, 4th Combat Engineer Battalion.
First Sergeant Grainger's personal decorations include the Navy and Marine Corps Commendation Medal and Navy and Marine Corps Achievement Medal with one star.