As a result of the joint German-Soviet invasion of Poland, which started World War II in September 1939, the town was occupied by Germany. The Germans immediately murdered several Poles and Jews and kidnapped others. Later on, Wieruszów was annexed directly to Nazi Germany. The Germans destroyed the monument of the heroes of the Greater Poland Uprising. Over the next two years, the Germans kidnapped Jews for forced labour, required them to live in a ghetto in the poorest part of town, turning over their former residences to Poles, and sent both men and women to work camps near Poznań. In August 1942, the remaining Jews were rounded up and held in a local monastery for several days. Several Jews were murdered there. Others were sent to the Łódź Ghetto, and the remainder, perhaps 800–900, were taken by train to the Chełmno extermination camp where they were immediately gassed. After that, local Poles were forced to move into the houses vacated by Jewish townspeople. After the war, a few Jewish survivors returned to Wieruszów but left after several Jews were murdered. The number of survivors is unknown.