A native of Virginia Beach, Virginia, Capt. Robert J. McMillan graduated from the U.S. Naval Academy, earning a Bachelor of Science in mechanical engineering and a commission as an ensign in May 2003. He is a graduate of the U.S. Naval Test Pilot School and holds a Master of Science in aeronautical engineering from the Air Force Institute of Technology. He is also a graduate of Aviation Safety Officer School

McMillan served operationally as an F/A-18E/F pilot in Strike Fighter Squadron (VFA) 213 deployed with Carrier Air Wing (CVW) 8 aboard USS Theodore Roosevelt (CVN 71) in support of Operation Enduring Freedom and VFA-154 aboard USS Nimitz (CVN 68).

His shore tours include service as a test pilot for weapons, systems, integration and software for the F/A-18 A-F in Air Test and Evaluation Squadron (VX) 31 and as Safety Officer and Flight Instructor in the Fixed Wing and Airborne and Unmanned Systems Syllabi at the U.S. Naval Test Pilot School.

As an acquisition officer, McMillan served as Integrated Product Team Lead for the Tactical Combat Training System Increment II program and Deputy Program Manager for Live Virtual Constructive (LVC) at PMA-205; Military Class Desk and Deputy Program Manager for Digital Engineering, Information Systems, and Infrastructure at the Next Generation Air Dominance Program Office, PMA-230; and as the Executive Assistant to the Principal Military Deputy for the Assistant Secretary of the Navy for Research, Development and Acquisition (ASN(RD&A)) at the Pentagon.

In September 2025, he assumed his current position as Program Manager for the Airborne Electronic Attack (AEA) Systems Program Office (PMA-234), providing acquisition, engineering, and technical services to the Navy and Marine Corps for the ALQ-249 Next Generation Jammer (NGJ) Mid-Band, ALQ-266 NGJ Low Band, AN/ALQ-99 Tactical Jamming System, AN/ALQ-231 Intrepid Tiger II, and Advanced AEA Development.

McMillan has accumulated over 2,200 flight hours in more than 40 different models of aircraft, including the F/A-18A-F, U-2, P-51, US-2, and Mirage 2000.