Glynn earned a Master of Science degree in National Security Affairs from the United States Army War College, a Master of Science degree in Military Studies from the Marine Corps Command and Staff College and is a graduate of the Marine Corps Amphibious Warfare School.

Glynn graduated from The Basic School and the Infantry Officers Course, then reported to 3rd Battalion, 3rd Marines at Marine Corps Base Hawaii in Kaneohe where he served as a rifle platoon commander throughout Operations Desert Shield/Desert Storm and later as the 81 mm Mortar Platoon Commander.

[5] Glynn's most recent assignments include: Military Assistant to the Assistant Commandant of the Marine Corps from July 2013 to August 2015 and then as the Director of the Office of U.S. Marine Corps Communication, Headquarters Marine Corps from Sept 2015 to Jun 2017; Deputy Commanding General of Special Operations Joint Task Force, Operation Inherent Resolve (Forward) from July 2017 to July 2018; Commanding General, Marine Corps Recruit Depot Parris Island and Eastern Recruiting Region and assumed duties as commanding officer of United States Marine Forces Special Operations Command on 26 June 2020.

[8] On 6 September 2022, Glynn was nominated for promotion to lieutenant general and assignment as deputy commandant for manpower and reserve affairs of the United States Marine Corps.

[9] On 23 October 2023, it was reported that President Joe Biden sent a delegation of officers including Glynn to advise the IDF during the Israel-Hamas war, based on their expertise from fighting ISIS in Mosul.