In 2006, Lieutenant Colonel Greenberg enlisted in the Marine Corps Reserve and served as a Field Radio Operator with Marine Wing Support Squadron 473. After graduating from San Diego State University with a Bachelor of Arts in Political Science, he received his commission as a Second Lieutenant in the Marine Corps.

After graduating from the Basic Officer and Infantry Officer Courses, Lieutenant Colonel Greenberg reported to 2d Battalion, 5th Marines in April 2010. Upon arrival, he assumed command of a rifle platoon in Company G, where he deployed with the 31st Marine Expeditionary Unit and conducted humanitarian assistance and disaster relief operations in support of Operation TOMODACHI. In June 2011, Lieutenant Colonel Greenberg was assigned as the Executive Officer of Company E, where he deployed in support of Operation ENDURING FREEDOM. In November 2012, he became the Executive Officer of Headquarters Company, 5th Marine Regiment.
In May 2013, Lieutenant Colonel Greenberg transferred to The Basic School and served as a Warfighting Instructor, Staff Platoon Commander, and Instructor Education Program/Master Instructor. In May 2017, he graduated with distinction from resident Expeditionary Warfare School.

After Expeditionary Warfare School, Lieutenant Colonel Greenberg commanded Company L, 3d Battalion, 1st Marines. During this tour, he deployed with the 13th Marine Expeditionary Unit, where Company L supported operations as an aviation assault/contingency force in the 5th and 7th Fleet areas of responsibility.

From May 2019 to June 2022, as a member of the Marine Corps Personnel Exchange Program, he served as a Company Commander with 40 Commando, Royal Marines, and U.K. Commando Forces. During this period, Lieutenant Colonel Greenberg deployed and led operations while driving the 'Generate the Force' initiative for Royal Marine/Navy Littoral Strike transformation. In June 2023, he graduated with distinction from resident Marine Corps Command and Staff College, was awarded the Krulak Center Award for Innovation, and received a Master of Military Studies degree.

After Command and Staff College, Lieutenant Colonel Greenberg joined 1st Marine Regiment as the Executive Officer for 1st Battalion, 4th Marines. Subsequently, he served as the Operations Officer for 1st Marine Regiment and Marine Rotational Force-Darwin 25.3.

On 18 June 2025, Lieutenant Colonel Greenberg assumed command of 3d Recruit Training Battalion, MCRD San Diego, where he currently serves.

Lieutenant Colonel Greenberg's personal awards include the Navy and Marine Corps Commendation Medal (second award), the Navy and Marine Corps Achievement Medal with "V," and the Combat Action Ribbon. Additionally, he is a 2021 recipient of the First Sea Lord's Commendation by Admiral Sir Antony Radkin, First Sea Lord, U.K. Royal Navy.