Sergeant Major Kirkby was born and raised in Watertown, New York. Following graduation from LaFargeville Central High School, he reported to Marine Corps Recruit Depot, Parris Island SC for Basic Training in August of 1998. He was then assigned to Personnel Administrative School where he was promoted to Private First Class and graduated February 1999. Upon graduation he reported to S1 Recruit Training Regiment, Marine Corps Recruit Depot, Parris Island SC. While assigned to RTR he was promoted to Lance Corporal October 1999, and Corporal May 2001.
In November 2002 he was promoted to the rank of Sergeant and received Regimental Special Orders to serve as the NCOIC for Recruit Processing Company, Support Battalion.
In July 2003 he reported to Drill Instructor School, Parris Island SC. Following graduation he attended Marine Corps Martial Arts Green Belt Instructor training and then assigned to Golf Company, Second Recruit Training Battalion where he served as a Drill Instructor until receiving a meritorious promotion to the rank of Staff Sergeant in January 2006. Where he then served as a Senior Drill Instructor and Series Gunnery Sergeant.
In February 2007 he reported to Camp Courtney, 3D Marine Division, Okinawa Japan where he was assigned as the Division Staff Secretary Admin Chief until being reassigned in December 2007 as the Admin Chief for G1 Adjutant Section. In October 2008 he deployed with 3D Marine Regiment out of Hawaii to Kandahar, Afghanistan where he was the Admin Chief for the Special Purpose Marine Air Ground Task Force - Afghanistan. He was promoted to the rank of Gunnery Sergeant March 2009 where he was assigned as the 3D Marine Division Adjutant Chief.
In May 2010 he reported to Cornell University where he served as the Assistant Marine Officer Instructor for the Naval ROTC program. While assigned as the AMOI he also worked four Officer Candidate School platoons as a Sergeant Instructor and Platoon Sergeant Instructor.
In September 2013 he received orders to Headquarters and Headquarters Squadron, Marine Corps Air Station, Beaufort SC where he was assigned as the Admin Chief. He was selected to the rank of First Sergeant in December 2014.
In February 2015 he reported to 1st Light Armored Reconnaissance Battalion, Camp Pendleton CA where he was assigned as the 1stSgt for Diablo Company and deployed with Battalion Landing Team 3/1, 15th Marine Expeditionary Unit aboard the USS Anchorage. Following deployment he served as the company 1stSgt for Charlie Company and Headquarters Company, and was selected to the rank of Sergeant Major in November 2018.
In February 2019 he reported for duty as the Sergeant Major for Marine Medium Tiltrotor Squadron 166, 3d Marine Aircraft Wing, Miramar. Deployed to Kuwait as the Aviation Combat Element Sergeant Major, attached to Special Purpose Marine Air Ground Task Force-Crisis Response-Central Command 20.2.
On 8 June 2021, he assumed Sergeant Major duties of Combat Instructor Battalion, The Basic School.
Sergeant Major Kirkby's personal awards include the Meritorious Service Medal with one gold star, Navy and Marine Corps Commendation medal with three gold stars, Navy and Marine Corps Achievement Medal with two gold stars.