Sergeant Major Janet Sandoval is a native of Chicago, Illinois. She graduated from Lane Technical High School in 2003 and enlisted into the United States Marine Corps the same year. Upon completion of recruit training at Marine Corps Recruit Depot Parris Island, South Carolina, she attended Marine Combat Training at Camp Geiger and Ground Supply School at Camp Johnson, North Carolina. She was assigned the military occupational specialty (MOS) 3051, Supply Warehouseman, and reported to Consolidated Supply Facility Company, 2nd Supply Battalion, 2nd Marine Logistics Group, Camp Lejeune.
In 2005, she deployed to Iraq in support of Operation Iraqi Freedom as a company clerk with Headquarters and Service Battalion, Combat Logistics Regiment 27. Upon redeployment, she was meritoriously promoted to the rank of Sergeant. In 2006, she joined Combat Logistics Battalion-2 as the Supply Warehouse Chief, and subsequently the Supply Administration Chief.
In 2007, she executed a lateral move to the MOS 3043, Supply Administration Specialist. After graduating from the Supply Administration Course, she reported to Marine Corps Air Facility Quantico as the Supply Chief, where she was named Noncommissioned Officer of the Year.
In 2010, she graduated from Drill Instructor School Class 2-10 at Parris Island and was promoted to Staff Sergeant. Assigned to Papa Company, 4th Recruit Training Battalion, she served as a Drill Instructor, Senior Drill Instructor, and Chief Drill Instructor. She also served as Receiving SNCOIC with Support Battalion.
In 2013, she reported to 1st Maintenance Battalion, Camp Pendleton, as the Repairable Issue Point Supply Administration Chief. In 2014, she deployed to Afghanistan with Combat Logistics Battalion-1 in support of Operation Enduring Freedom, where she served as the Repairable Issue Point and Communications Electronics Maintenance SNCOIC.
From 2016 to 2018, she served as Logistics Chief for Recruiting Station Chicago. She was subsequently served as an instructor at Officer Candidates School (OCS) aboard Marine Corps Base Quantico where she held multiple billets, including Sergeant Instructor, Platoon Sergeant, Academics Instructor, and Assistant Family Readiness Officer.
In 2019, she reported to 3d Maintenance Battalion, Okinawa, Japan, and was promoted to First Sergeant. She held the billet of Company First Sergeant for Engineer Maintenance Company, Headquarters and Service Company, and Motor Transport Maintenance Company. In 2021, she transferred to 3d Supply Battalion as the Supply Company First Sergeant.
In June 2022, Sergeant Major Sandoval reported to the School of Infantry–West and served as the Senior Enlisted Leader for the Infantry Marine Course and Headquarters and Instructor Company. She was promoted to her current rank in April 2025.
In May 2025, Sergeant Major Sandoval reported for duty as the Command Senior Enlisted Leader, Recruiting Station Chicago, 9th Marine Corps District.
Sergeant Major Sandoval's personal awards include the Navy and Marine Corps Commendation Medal in lieu of fourth award and the Navy and Marine Corps Achievement Medal in lieu of second award.