Sergeant Major Kenneth S. Williamson is a native of Indiana. He enlisted in the Marine Corps on 17 April 2005. He attended recruit training at Marine Corps Recruit Depot, San Diego, California. After graduating, he attended Marine Combat Training (MCT) at Camp Pendleton, California. Following completion of MCT he attended MOS school at Naval Air Station Pensacola, Florida, for Flight Equipment Technician.

In November 2005, Sergeant Major Williamson received orders to Marine Attack Fighter Squadron 122 (VMFA-122) where he served as a Flight Equipment Technician. While there, Sergeant Major Williamson received orders to participate in the Unit Deployment Program with VMFA-122 to Iwakuni, Japan. While there, he supported three deployments throughout Japan, the Philippines, and Thailand. In September 2008, Sergeant Major Williamson deployed to Al Asad, Iraq, in support of Operation Iraqi Freedom.

In January 2010, Sergeant Major Williamson received orders to Drill Instructor School Class 2-10, Marine Corps Recruit Depot, San Diego, California. Upon completion of Drill Instructor School, Sergeant Major Williamson was assigned to Company D, First Recruit Training Battalion where he served as Drill Instructor, Senior Drill Instructor, and Chief Drill Instructor. 

In October 2012, Sergeant Major Williamson was transferred to Instructor Staff, Drill Instructor School MCRD, San Diego, California.

In May 2013, Sergeant Major Williamson received orders to Marine Aviation Logistics Squadron 36 where he served as a Flight Equipment Technician, Quality Assurance Representative, and 800 Division Chief.

In January 2015, Sergeant Major Williamson received orders to Marine Medium Tiltrotor Squadron 265 where he served as a Flight Equipment Technician, Quality Assurance Representative, and Flight Equipment Division Chief. While there, he was attached to the 31st Marine Expeditionary Unit in support of multiple operations in the Pacific theatre.

In June 2016, Sergeant Major Williamson reported to Marine Corps Security Force Battalion, Kings Bay, Georgia. He was the Company A First Sergeant from April 2016 to February 2019 and the Headquarters and Service Company First Sergeant from February 2019 to June 2019.

In June 2019, Sergeant Major Williamson reported to 1st Transportation Battalion, Camp Pendleton, California. He was the Company B First Sergeant from June 2019 to October 2019. He was TAD to Combat Logistics Detachment 25 from October 2019 to December 2020 as the Senior Enlisted Leader in support of the Logistics Combat Element, SPMAGTF-CR-CC 20.2. He then served as the Headquarters and Service Company First Sergeant from December 2020 to June 2021.

In July 2021, Sergeant Major Williamson reported to First Recruit Training Battalion, Marine Corps Recruit Depot, Parris Island.

Sergeant Major Williamson's personal decorations include the Navy and Marine Corps Commendation Medal with three gold stars in lieu of fourth award and the Navy and Marine Corps Achievement Medal with one gold star in lieu of second award.