Sergeant Major Mitchell enlisted in the Marine Corps on 8 August 1990 and attended boot camp at Marine Corps Recruit Depot Parris Island, South Carolina.
Sergeant Major Mitchell attended Marine Combat Training and the School of Infantry for training as a 0311, Infantryman. He was assigned to 2nd FSSG, Camp LeJuene, North Carolina was attached to a CRC unit (Combat Replacement Company) and deployed to Saudi Arabia where he participated in several combined missions in support of Operation Desert Shield/Desert Storm.
In August 1991, he was assigned to 1st Battalion 8th Marines where he deployed to the Mediterranean Sea in support of Operation Desert Shield/Desert Storm in Saudi Arabia, attached to Joint Task Force (JTF-160) in support of Operation Sea Signal in Cuba, and Operation Deny Flight in Bosnia.
In May 1994, Sergeant Major Mitchell was assigned to MALS-26/MAG-26, New River Air Station, North Carolina as the S-3 Training Non-Commissioned Officer. In March 1997, he was assigned to 3rd Battalion 6th Marines, where held many infantry billets from Team Leader to TOW Gunner Section Leader. He deployed to the Mediterranean Sea in support of Operation Restore Hope in Somalia, Operation Joint Guardian in Kosovo, and Operation Noble Eagle in Albania.
In November 2000, Sergeant Major Mitchell was assigned to the School of Infantry (SOI EAST), Infantry Training Battalion (ITB), as a 0311 Platoon Commander. In May 2002, he was assigned as a Drill Instructor for 1st Recruit Training Battalion, Parris Island, South Carolina.
In June 2005, Sergeant Major Mitchell was assigned to 1st Battalion, 8th Marines, as a Company Gunnery Sergeant. He participated in humanitarian evacuation support operations in Lebanon, disaster relief for Hurricane Katrina in New Orleans, Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF). Sergeant Major Mitchell was assigned to Fort Devens, Massachusetts as the I&I First Sergeant for Ordnance Maintenance Company in August 2008 and was transferred to 1st Battalion, 25th Marines, Bravo Company, Londonderry, New Hampshire as the I&I First Sergeant.
In June 2011 Sergeant Major Mitchell was assigned to 3rd Battalion, 10th Marines and deployed with 24th MEU. Upon completion of the deployment he was assigned to 2D Anglico, II MEF in February 2013 as the Sergeant Major. In November 2014 Sergeant Major Mitchell was assigned to MWSS-272 as the Squadron Sergeant Major.
Sergeant Major Mitchell’s personal awards include the Meritorious Service Medal with a Gold Star, Navy and Marine Corps Commendation Medal with four Gold Stars, Navy and Marine Corps Achievement Medal with a Gold Star, Combat Action Ribbon, Humanitarian Service Medal with two Bronze Stars, Outstanding Volunteer Service Medal, and Army Achievement Medal.