Lieutenant General Smith is from Plano, Texas and entered the Marine Corps in 1987 through the NROTC program at Texas A&M University. After completing The Basic School and Infantry Officer's Course, he was assigned to 2nd Battalion, 3rd Marines; participating in Operations Desert Shield / Desert Storm. Following a tour as an Officer Selection Officer, he attended the Amphibious Warfare School and then reported to 2nd Battalion, 2nd Marines for duty as Commanding Officer of Weapons and Echo Companies. During this tour he participated in Operation Assured Response in Monrovia, Liberia.

After a tour as a Marine Officer Instructor at Texas A&M University, he attended the United States Army Command and General Staff Course. His next assignment was as the Naval Section Chief at the U.S. Military Group in Caracas, Venezuela from 2001-2003.

From 2003 until 2006, he served in the 1st Marine Division as the Division Current Operations Officer; Executive Officer of Regimental Combat Team 1; Commanding Officer of 1st Battalion, 5th Marines; and Assistant Chief of Staff G3. During this period he completed two deployments to Iraq in support of Operation Iraqi Freedom. Subsequent assignments were as a student at the Marine Corps War College, Senior Aide to the Commandant of the Marine Corps, and Director of the Fires and Maneuver Integration Division at the Marine Corps Combat Development Command.

From 2009 until 2012 he served in the 2nd Marine Division as the Assistant Chief of Staff G3 and Commanding Officer of 8th Marine Regiment; completing a one-year deployment to Afghanistan in support of Operation Enduring Freedom.

In June of 2012 he reported for duty as the Director of Capability Development Directorate, and in May of 2013 he was assigned as the Senior Military Assistant to the Deputy Secretary of Defense.

From July through November of 2015 he commanded Marine Corps Forces Southern Command in Miami, Florida, and was then transferred to the Pentagon to serve as the Senior Military Assistant to the Secretary of Defense. From February 2017 until June 2017, he served as the Assistant Deputy Commandant for Plans, Policies and Operations. From June 2017 until July 2018, he served as the Commanding General, 1st Marine Division. From August 2018 until June 2019, Lieutenant General Smith served as the Commanding General, III Marine Expeditionary Force.

On 13 June 2019, Lieutenant General Smith assumed responsibility as the Commanding General, Marine Corps Combat Development Command, and the Deputy Commandant for Combat Development and Integration, Headquarters, U.S. Marine Corps.