[2] Vivacious remained in commission after the United Kingdom entered World War II in September 1939, Assigned to the 17th Destroyer Flotilla at Plymouth for convoy escort and patrol duties in the English Channel and the Southwestern Approaches, she escorted an 18-ship convoy carrying supplies, ammunition, and vehicles for the British Expeditionary Force from the United Kingdom to Cherbourg, France, on 10 September 1939.

She began patrols the following day to protect the evacuation beachhead from attacks by German aircraft and motor torpedo boats (S-boats, known to the Allies as "E-boats").

She also took part in Operation OK on 3 June 1940, in which blockships were sunk to block the harbor at Dunkirk; she took aboard the crews of the sunken ships and brought them to Dover.

[4] After the evacuation was complete, Vivacious was transferred to the 21st Destroyer Flotilla at Sheerness on 7 June 1940 for convoy escort and anti-invasion patrol duty in the North Sea.

In 1941, after the threat of invasion subsided, she began to participate in the interception of German S-boats in the North Sea to prevent them from attacking convoys in addition to her other duties.

She was "adopted" by the civil community of Solihull, then in Warwickshire, in March 1942 in a Warship Week National Savings campaign, and she collided with the destroyer HMS Vesper on 31 August 1942.

[2] In May 1944, Vivacious was selected to form Escort Group 103 with Campbell, the corvettes HMS Clover and HMS Pennywort, and Motor Launches of the Coastal Forces to operate in Force L during Operation Neptune to provide escort for convoys bringing reinforcements and supplies to the beachhead in the days following the initial assault of the Allied invasion of Normandy.

[2] In July 1944, Vivacious returned to the 21st Destroyer Flotilla and convoy escort and patrol duties in the North Sea and English Channel, continuing them until the surrender of Germany in early May 1945.