After the start of World War II in September 1939, she blockaded the Polish coast and searched neutral shipping for contraband.

The Wagner geared steam turbines were designed to produce 70,000 metric horsepower (51,485 kW; 69,042 shp) which would propel the ship at 36 knots (67 km/h; 41 mph).

[7] Bruno Heinemann sailed in company with her sister Z5 Paul Jakobi to Norway in April 1938 to test the new 15-centimeter (5.9 in) TbtsK C/36 gun planned for later classes of destroyers.

[8] When World War II began, Bruno Heinemann was initially deployed in the Baltic to operate against the Polish Navy and to enforce a blockade of Poland,[10] but she was soon transferred to the German Bight where she joined her sisters in laying defensive minefields.

After completing her refit, Bruno Heinemann and Paul Jakobi were bound for the Baltic via the Kiel Canal when they were attacked by 11 Handley Page Hampden bombers of No.

[12][13] Although the other destroyers were busy escorting the German heavy ships and laying minefields off the British coast in October and November,[14] Bruno Heinemann played no part of any of these operations until the night of 12/13 December.

Despite their escort, the submarine HMS Ursula managed to sneak inside the anti-submarine screen and fired a salvo of six torpedoes at Leipzig in the Elbe estuary.

[21] Bruno Heinemann and her sisters Paul Jakobi and Theodor Riedel each carried a company of mountain troops tasked to seize the forts defending the entrance to the Trondheimsfjord.

Fuel was transferred from Bruno Heinemann and Paul Jakobi to Friedrich Eckoldt sufficient to give the heavy cruiser some anti-submarine protection.

[24] The ship escorted a force of minelayers on the nights of 29/30 April and 9/10 May 1940 in the vicinity of the Great Fisherman's Bank, but the second sortie turned back when British destroyers were spotted.

On 5 April 1941, Bruno Heinemann left Germany for Occupied France and she was attacked by two torpedo bombers en route, but suffered no damage.

The ship and the other destroyers present escorted commerce raiders, blockade runners and major warships as they used the French Atlantic coast ports until she was recalled on 6 September for another refit.

[27] Bruno Heinemann, together with the rest of the 5th Destroyer Flotilla, sailed from Kiel on 24 January for France as part of the preparations for the Channel Dash.