First Sergeant Leonardo A. Cancinos is a native of Bronx, New York. In August 2005 he enlisted in the Marine Corps and attended recruit training at Kilo Company, 3rd Recruit Training Battalion, Marine Corps Recruit Depot Parris Island, South Carolina. In December 2005, he then reported to the School of Infantry, Camp Geiger, North Carolina for Infantry Training, where he earned the MOS of 0311.

In March 2006 upon completion of school, Private First Class Cancinos reported for duty at the Anti-Terrorism Battalion 4th Marine Expeditionary Brigade, Camp Lejeune, North Carolina. He was assigned to Bravo Company and in August of 2006 he took part in a unit deployment to Baghdad, Iraq. In October 2006, he was promoted to the rank of Lance Corporal and assigned as Team Leader 2nd fire team 1st squad. He returned from his deployment in September 2007.

In November 2007, Lance Corporal Cancinos volunteered to deploy with Task Force Military Police and received orders to report to the 3rd Battalion 10th Marines, Camp Lejeune, North Carolina. He was assigned to Military Police Company, 1st platoon, 1st squad, 1st vehicle commander. In March 2008, he took part in the unit deployment to Ramadi, Iraq. In August 2008, he was promoted to the rank of Corporal and was assigned as the Guard Commander for 1st platoon and Personnel Security Detachment Commander for the RCT Commander.

In January 2009, Corporal Cancinos received orders to Marine Headquarters Group, Camp Lejeune, North Carolina, where he was assigned to Military Transition Team 0110, as an Advisor. In June 2009, he took part in the unit deployment to Bashara, Iraq. While there, he served as the 14th Division Iraqi Army, Personnel Security Detachment Advisor.

In December 2010 Corporal Cancinos graduated Marine Combat Instructor School, and reported to Delta Company, Infantry Training Battalion. On January 1st, 2011, he was promoted to the rank of Sergeant. While serving in Delta Company as a Combat Instructor, Sergeant Cancinos was assigned as the Patrolling, Offense, Military Operations on Urban Terrain, Weapons and Munitions, and Physical Training Package leader. In April 2013, he was selected by the Infantry Training Battalion Commander to serve in the Operations Section as the Scheduling Chief.

In Dec 2013 Sergeant Cancinos reported to 2nd Battalion 9th Marines, Camp Lejeune, North Carolina. He was assigned to Weapons Company and served as Section Leader, Combined Anti-Armor Team One. In August 2014, he took part in the Unit Deployment Program to Okinawa, Japan.

In April 2015, Sergeant Cancinos reported to 1st Battalion 8th Marines. He was assigned to Weapons Company and served as a Section Leader, Combined Anti Armor Platoon. In Nov 2015, he was promoted to the rank of Staff Sergeant and was selected to serve as a Platoon Commander ,6th Platoon, Bravo Company, while attached to Special Purpose Marine Air-Ground Task Force-Crisis Response Africa (SPMAGTF-CR AF) as the Alert Company. In January 2016, he took part in the unit deployment to Moron, Spain. In February Staff Sergeant Cancinos conducted a turnover with the new Platoon Commander and was made the Platoon Sergeant 6th platoon, until he returned from deployment in August 2016.

In January 2017 Staff Sergeant Cancinos reported to Marine Combat Instructor School, School of Infantry East. He graduated January 30th, 2017, and received orders to Bravo Company, Infantry Training Battalion. In May 2017, he was selected to serve as a Combat Instructor Trainer, for Marine Combat Instructor School, and later was selected to become the Chief Instructor for the Marine Combat Instructor School in October 2018. In November 2019, he was promoted to the rank of Gunnery Sergeant.

In March 2020, due to the Covid-19 pandemic, Gunnery Sergeant Cancinos was selected to serve as Operations Chief, Headquarters and Support Battalion, School of Infantry-East until he executed orders to Marine Corps Training Mission-United Arab Emirates in July 2020. While stationed in the United Arab Emirates he served as an Advisor and Trainer to the Long-Range Reconnaissance Battalion and the Unmanned Aerial Surveillance Battalion, of the Presidential Guard Reconnaissance Command. Subsequently, he was selected to serve as the Deputy Advisor for the Reconnaissance Command, a billet normally given to a Major.

In October 2021, Gunnery Sergeant Cancinos reported to Bravo Company, 1st Battalion 2nd Marines where he served the Support Platoon Sergeant/Company Operations Chief. In March 2023, he was promoted to the rank of First Sergeant and served as the Headquarters and Service Company, Company First Sergeant.

In July 2023, First Sergeant Cancinos assumed the billet of Unit Senior Enlisted Leader of Site-Support Broken Arrow OK, where he is currently serving.

First Sergeant Cancinos' personal awards include the Navy Commendation Medal with 2 gold stars in lieu of 3rd award and Navy and Marine Corps Achievement Medal with 2 gold stars in lieu of 3rd award.