Colonel Mulvihill was commissioned through the Reserve Officer Training Corps as a second lieutenant in May 1997 and earned a Bachelor of Science degree in Marine Transportation from the State University of New York, Maritime College.
Upon graduation from Infantry Officer Course in March 1998, Second Lieutenant Mulvihill was assigned to 1st Battalion, 2d Marine Regiment, Camp Lejeune, North Carolina where he served as Weapons Platoon Commander, 81mm Mortar Platoon Commander, Weapons Company Executive Officer and Weapons Company Commander. He deployed with 1/2 as the 81mm Mortar Platoon Commander to Okinawa under the Unit Deployment Program.
From March to September 2000 First Lieutenant Mulvihill was a student in the Defense Language Institute Advanced Spanish Course aboard Camp Lejeune. Upon graduation he was assigned to II Marine Expeditionary Force, II MEF Headquarters Group as the Headquarters Company Commander and S3A. He was then assigned to Special Operations Training Group, II MEF as the S3A. While at SOTG 1stLt Mulvihill deployed to Puerto Leguizamo, Colombia as an Instructor on Riverine Training Team 1-01.
In December 2001 Captain Mulvihill transferred to United States Marine Corps Forces, South, Miami, Florida where he served as the Counter-Narcoterrorism Operations Officer. While at MARFORSOUTH he deployed to Bogota, Colombia and served as the Riverine Plans Officer and then to Iraq as the Officer in Charge, Advisor Team to an Iraqi Army Infantry Battalion where he participated in Operation AL FAJR in November 2004.
In May 2005 Capt Mulvihill, enroute to Expeditionary Warfare School, Quantico, Virginia, was assigned to Officer Candidate School as a Platoon Commander. Upon graduation from EWS in 2006 he was assigned to Battalion Landing Team 2/2, Camp Lejeune, North Carolina where he deployed as the Mechanized Company Commander for the 26th Marine Expeditionary Unit (Special Operations Capable). Upon returning from deployment Major Mulvihill assumed the duties of Staff Secretary for 2d Marine Division. He was then transferred to 3d Battalion, 8th Marine Regiment where he deployed to Afghanistan as the Executive Officer in support of Operation ENDURING FREEDOM in 2008.
After redeploying Maj Mulvihill was assigned to Manpower Management, Officer Assignments, Manpower and Reserve Affairs in Quantico, Virginia and served as the Combat Arms Majors Monitor from 2009 to 2011. He was then transferred to 2d Marine Regiment, Camp Lejeune, North Carolina where he served as the Operations Officer. Maj Mulvihill then assumed the duties of OIC, Advisor Team to an Afghan National Army Infantry Battalion and deployed to Sangin District, Helmand Province in support of OEF in 2013.
During September 2013 Lieutenant Colonel Mulvihill was transferred to United States Africa Command, where he served as the J37 East and Central Counter Terrorism Branch Chief and the J35 Future Operations Officer for East, Central, and South Africa. On 11 July 2016, LtCol Mulvihill assumed command as Inspector & Instructor, 1st Battalion, 24th Marines and served in that billet for two years. On 13 June 2019 he was a Distinguished Graduate of the College of International Security Affairs, National Defense University, earning a Master of Arts in Strategic Security Studies. LtCol Mulvihill was then assigned as a Senior Fellow at the Center for Strategic and International studies.
In July 2020, Colonel Mulvihill assumed the duties of Assistant Chief of Staff/G3 for United States Marine Forces, Europe and Africa. On 23 June 2023, Col Mulvihill assumed command of 5th Marine Regiment.
Col Mulvihill's personal awards include the Legion of Merit, the Bronze Star Medal with valor device and gold star, the Defense Meritorious Service Medal, the Meritorious Service Medal with gold star, the Joint Service Commendation Medal, the Navy and Marine Corps Achievement Medal and the Combat Action Ribbon with gold star.