A veteran of several campaigns in Pacific during World War II, he distinguished himself during the Battle of the Coral Sea in May 1942, while commanding destroyer Morris and received the Navy Cross, the second highest decoration of the United States military.

Jarrett served as ship's engineer officer under lieutenant commander John H. Brown Jr. and participated in the sea trials off the Boon Island in Gulf of Maine.

[1][11][12] Jarrett was ordered to United States Naval Academy at Annapolis, Maryland, in June 1937 and assumed duty as a discipline officer on the staff of Superintendent, Rear admiral David F. Sellers.

During his service at the academy, Jarrett was promoted to lieutenant commander on 23 June 1938 and also completed correspondence course in international law at the Naval War College in Newport, Rhode Island.

At the time of Japanese attack on Pearl Harbor and the United States entry into World War II, Jarrett's Morris was still located in the Atlantic.

He immediately received orders to sail for Pearl Harbor, Hawaii, to join Task Force 17 under vice admiral Frank J. Fletcher and was promoted to the temporary rank of commander on 1 January 1942.

[17][1] Jarrett later served as destroyer screen commander for convoy escort and shore bombardment during the Mariana Islands campaign, participating in the assaults on Saipan, Tinian, and Guam in June–August 1944 and received a Gold star in lieu of second Legion of Merit with Combat "V" for distinguished service.

Jarrett then led his reinforced squadron of nine Fletcher-class destroyers during the battles in the vicinity of Ryukyu Islands and Tokyo and received Bronze Star Medal with Combat "V".

Jarrett served consecutively under admirals Louis E. Denfeld, Forrest P. Sherman, and William M. Fechteler, before assumed duty as the first U.S. Senior Military Attaché, Formosa (Taiwan) in July 1950.

Jarrett remained in that capacity until November 1951, when he was recalled to the United States and received Collar Order of the Cloud and Banner by the Government of Republic of China for his service.

He served in this capacity until February 1953, when he was ordered back to Washington, D.C., and assumed duty as Deputy Naval Inspector General under Rear admiral J. Cary Jones.

Vice admiral Harry B. Jarrett was buried with full military honors at the United States Naval Academy Cemetery at Annapolis, Maryland.