After her commissioning the HNLMS O 19 was put into service by commander Lieutenant-on-sea 1 (LTZ 1) K. van Dongen on July 3, 1939, following a short training period.

[citation needed] Most Dutch warships, including the O 19, were used to protect allied merchant ships and to patrol the Indonesian archipelago.

[4] The submarine performed patrols and missions in the Pacific theater, sinking several Japanese vessels, attacking convoys and laying mines.

[6] On 8 July 1945, O 19 was en route to Subic Bay in the Philippines at a speed of 16 knots (30 km/h; 18 mph) when it struck Ladd Reef in the South China Sea.

[8] The diesel engines for the HNLMS O 19 was built under the license of the Swiss Sulzer by the Koninklijke Maatschappij De Schelde in Vlissingen.