Geulen was a young teacher working in a Brussels school when the Second World War broke out. When a raid was to take place in the boarding school during the Whitsun weekend in 1943, she warned the Jewish families. She then joined the resistance movement Jewish Defense Committee.
Andrée Geulen-Herscovici himself brought more than 300 Jewish children to foster homes, where they could stay under a false identity. The Jewish Defense Committee thus succeeded in putting about 3,000 Jewish children into hiding.
After the war, Geulen-Herscovici made every effort to reunite the children with their parents.
Geulen-Herscovici was named honorary citizen of Ixelles in March.