Lieutenant Colonel (LtCol) O'Brien was born in Philadelphia, PA and graduated from Cheltenham (PA) High School in 1999.  He later graduated from the United States Naval Academy with a Bachelor of Science Degree in Systems Engineering and was commissioned a Second Lieutenant in the USMC on 23 May 2003.  Following the Naval Academy, as part of the Immediate Graduate Education Program, LtCol O'Brien attended the Massachusetts Institute of Technology.  He completed the course of study in December 2004 with a Master of Science Degree in Mechanical Engineering. 

LtCol O'Brien completed The Basic School with Bravo Company in July 2005.  He subsequently conducted flight training at NAS Pensacola, FL, NAS Corpus Christi, TX, and NAS Kingsville, TX, prior to receiving his “Wings of Gold” on 8 February 2008.  He was promoted to the rank of Captain in July 2007.

LtCol O’Brien reported to MCAS Miramar, CA in February 2008 to join the VMFAT-101 Sharpshooters while training to become an F/A-18 Hornet pilot.  When complete with training in September 2009, he reported to the VMFA-323 "Death Rattlers."  LtCol O'Brien subsequently executed two combat deployments to the 5th and 7th Fleet Areas of Responsibility - the first in 2011 with CVW-14 onboard the USS Ronald Reagan (CVN 76) and the second in 2013 with CVW-11 onboard the USS Nimitz (CVN 68).  During these deployments, he supported Operations Tomodachi in Japan, New Dawn in Iraq, and Enduring Freedom in Afghanistan as well as contingency operations in the Horn of Africa during the 2013 Syrian unrest.  While at VMFA-323, LtCol O'Brien graduated from the U.S. Navy Strike Fighter Tactics Instructor Program (TOPGUN) and held the billets of Logistics Officer, Airframes Officer, Pilot Training Officer, and Director of Safety and Standardization.  He was promoted to the rank of Major in November 2013.

LtCol O'Brien reported to the VMFA-121 "Green Knights" in December 2013 in Yuma, AZ.  Soon thereafter, as Director of Safety and Standardization, he played a critical role as one of the Marine Corps' first four F-35 Instructor Pilots during the Green Knights' training for the declaration of F-35B Initial Operational Capability (IOC) in July 2015.  Subsequently, as Pilot Training Officer, LtCol O'Brien successfully prepared students for the first four classes of the F-35 Weapons and Tactics Instructor (WTI) course.  In 2016, he assumed the role of Operations Officer while the Green Knights were the first F-35 participants from any service in Exercise Red Flag - the U.S. Air Force's premiere multi-domain joint integration exercise.  In January 2017, LtCol O'Brien was the lead planner and action officer for the first ever F-35 Trans-Pacific flights during the permanent relocation of VMFA-121 and its F-35B aircraft from MCAS Yuma, AZ to MCAS Iwakuni, Japan.  In August 2017, LtCol O'Brien reported to MAG-12 as the Future Operations Officer, and later Plans Officer, before reporting back to VMFA-121 as the Executive Officer in October 2018.  While in Japan, he was instrumental in F-35 integration into existing OPLANs as well as the first F-35 participation in Exercises Northern Edge, Vigilant Ace, Valiant Shield, and Balikatan - the latter being the first operational shipboard deployment of ten F-35Bs.  LtCol O'Brien proudly served with VMFA-121 as they were awarded the 2019 Commandant's Aviation Trophy for outstanding contribution to Marine Corps Aviation.  

In May 2019, LtCol O'Brien transferred to Headquarters, Marine Corps, Aviation as a member of the 'F-35 Cell' in the billet of F-35 Transition Task Force Lead.  In that role, he synchronized the legacy-to-F35 Transition Plan across multiple entities both internal to, and external to, the USMC.  He also served as the lead F-35 Action Officer in the effort to reorganize and restructure the Marine Corps as part of the CMC's Force Design 2030 initiative.  He was promoted to the rank of Lieutenant Colonel in October 2019 and was later selected to command the VMFA-314 "Black Knights" - the Marine Corps' only operational F-35C squadron. 

LtCol O'Brien returned to MCAS Miramar in January 2021 and filled an interim billet as the MAG-11 Plans Officer prior to taking command of the Black Knights.  In that role, he worked with Marine Corps, Joint, and Coalition personnel to realign existing OPLANs in the Indo-Pacific region with USMC strategic goals and initiatives.  LtCol O'Brien assumed command of VMFA-314 on 9 September 2022.     

LtCol O'Brien's personal awards include two Meritorious Service Medals, a Strike/Flight Air Medal, and a Navy and Marine Corps Commendation Medal.  LtCol O’Brien is married to LtCol Courtney Davidson O'Brien of New Oxford, PA.  She is a KC-130J pilot and assumed command of the VMGR-352 Raiders, also on 9 September 2022.