Lieutenant Colonel Mark Lenzi was commissioned in 2005 after graduating from The Virginia Military Institute with a Bachelor of Arts degree in Economics and Business. His initial assignment was with 2d Battalion, 7th Marine Regiment in Twentynine Palms, CA from 2006 to 2009. He served in Operation IRAQI FREEDOM as a Platoon Commander and in Operation ENDURING FREEDOM as the Executive Officer for Company G. 
 
In June of 2009, Lieutenant Colonel Lenzi reported to The Basic School, where he served as an instructor in the Warfighting Section. In June 2010, Lieutenant Colonel Lenzi was assigned to the Infantry Officer Course, where he instructed until 2012. Lieutenant Colonel Lenzi then attended Expeditionary Warfare School, Academic Year 2013. 

In May of 2013, Lieutenant Colonel Lenzi reported to 2d Battalion, 5th Marine Regiment in Camp Pendleton, California. He served as the Company Commander for Weapons Company during the battalion’s deployment as the Battalion Landing Team for the 31st Marine Expeditionary Unit from 2013 to 2014. 

In September 2014, Lieutenant Colonel Lenzi checked in to the Ground Combat Element Integrated Task Force in Camp Lejeune, North Carolina. Captain Lenzi assumed command of Weapons Company through the service level assessment aboard the Marine Corps Air Ground Combat Center in Twentynine Palms, CA, and the Mounter Warfare Training Center in Bridgeport, CA.

In June of 2015, Lieutenant Colonel Lenzi joined the 4th Reconnaissance Battalion in San Antonio, Texas, where he was assigned as the Inspector-Instructor for Company C. In March 2016, Lieutenant Colonel Lenzi completed the Basic Reconnaissance Course. In December 2016, Lieutenant Colonel Lenzi was reassigned as the Battalion Operations Officer, where he served until May 2018. 

From June 2018 to June 2021, Lieutenant Colonel Lenzi served as the Commanding Officer for Recruiting Station Tampa in Tampa, FL. In June 2021, Lieutenant Colonel Lenzi joined 3d Marines as the Executive Officer.

Lieutenant Colonel Mark A. Lenzi assumed duties of Commanding Officer of 3d Littoral Combat Team, 3d Marine Littoral Regiment on June 23, 2022.