Rear Admiral Guillory, a native of New Orleans, graduated from the U.S. Naval Academy in 1978 with a Bachelor of Science in Management and Technology. His early sea assignments were aboard the guided-missile destroyer USS Towers (DDG 9), the guided-missile frigate USS Lewis B. Puller (FFG 23), the cruiser USS Vincennes (CG 49) and as the commissioning executive officer in the cruiser USS Gettysburg (CG 64). He commanded the guided-missile frigate USS Underwood (FFG 36) and the cruiser USS Lake Champlain (CG 57).

Ashore, Guillory's assignments included several Washington area tours in Office of the Chief of Naval Operations, Surface Warfare Division, as branch head for Combat Systems, and as the assistant deputy director for Surface Ships. He also served in the Joint Staff as the J-38, Current Readiness branch chief.

Guillory was selected for flag officer in early 2004 and assumed command of Amphibious Force, U.S. 7th Fleet and Amphibious Group 1 in October 2004. During this tour, he was responsible for Joint and Combined amphibious operations throughout the Western Pacific. In addition, he served as the deputy commander of U.S. Naval Forces for Combined Support Force 535 (Southeast Asia Tsunami Relief Operations) in early 2005.

In December 2006, Guillory returned to Washington D.C. and the Office of the Chief of Naval Operations as the deputy director of Surface Warfare (OPNAV N86B). He assumed the duties as director of Surface Warfare in October 2007 and the responsibility for the warfighting requirements and resources for all surface combatant ships and combat systems.

In June 2009, Guillory was selected to assume command of U.S. Naval Forces Southern Command/U.S. 4th Fleet. Immediately following the devastating 7.0 earthquake in Port-au-Prince, Haiti in January 2010, 4th Fleet coordinated the U.S. Navy’s response to the disaster relief operations. Fourth Fleet exercised command and control of approximately 15,000 Sailors and Marines and nearly two dozen ships and embarked aircraft in direct support of the larger U.S. government effort.

Guillory is a graduate of the National Defense University (Industrial College of the Armed Forces) and his personal awards and decorations include the Legion of Merit, Defense Meritorious Service Medal, two Meritorious Medals, the Navy Commendation Medal with Gold Star and Combat "V" and various campaign medals. He is also a 2009 recipient of the Black Engineer of the Year Award for Leadership.