Sergeant Major Janssen enlisted in the Marine Corps in 2000 and reported to recruit training at Marine Corps Recruit Depot, Parris Island, SC on January 8th, 2001. Upon Completion of recruit training, MCT and Aircraft Rescue and Fire Fighting training. PFC Janssen was assigned to Marine Wing Support Squadron 473 Det(-), Marine Corps Air Station, Miramar, CA.
In 2003, while with MWSS 473 Det (-), Lance Corporal Janssen was mobilized in support of Operation Iraqi Freedom /Enduring Freedom and held the billet of platoon administrative chief. During this activation she was also elected to be the president of the MCAS Miramar Single Marine Program. She was meritorious promoted to Corporal and received a Navy and Marine Corps Achievement Medal for her contributions during the activation.
In 2004, while in the billet of rescueman, Corporal Janssen received the Marine Corps Institutes Student of the Year Award and received a Navy and Marine Corps Achievement Medal for her efforts. Corporal Janssen was meritoriously promoted to Sergeant and assumed the billet of section leader.
In 2006 Sergeant Janssen assumed the position of the detachment career planner. She maintained this billet until being promoted to Staff Sergeant May 1, 2009 and joined the Individual Marine Augmentee (IMA) program in 2009.
Upon transfer to the IMA in 2009, Staff Sergeant Janssen joined MWSS 372 at Marine Corps Air Station, Camp Pendleton, CA. In 2010 Staff Sergeant Janssen mobilized for 6 months and filled the billet of platoon administrative chief and reserve liaison. She was promoted to Gunnery Sergeant March 1, 2014 and returned to the Select Marine Corps Reserve January 2015.
Gunnery Sergeant Janssen assumed the billet of Company Gunnery Sergeant for Headquarters and Service Company, Marine Wing Support Squadron 473 (-) in January 2015. She assumed the billet of acting First Sergeant in June of 2015 and held that billet until 2018 when she was promoted to the rank of First Sergeant and assumed the billet of Company First Sergeant at Engineer Services Company, Combat Logistics Battalion 23, Springfield Oregon in May 2018. During her time with Engineer Services Company First Sergeant Janssen was an instructor at the First Sergeant Symposium.
In 2020 First Sergeant Janssen joined Alpha Company, Counterintelligence/Human Intelligence, Intelligence Support Battalion as Company First Sergeant. In 2021 she assumed the billet of Squadron Sergeant Major at Marine Tactical Air Command Squadron 48 and remained there after her promotion to Sergeant Major in 2023, and then joined 4th Medical Battalion as their Command Senior Enlisted Advisor in June 2024.
First Sergeant Janssen earned a Bachelor of Arts degree in English from California State University Fullerton and Master of Arts in Organizational Leadership from Concordia University, Irvine.