Irène took a nursing course during college to assist her mother, Marie Curie, in the field as her assistant. She began her work as a nurse radiographer on the battlefield alongside her mother, but after a few months she was left to work alone at a radiological facility in Belgium. She taught doctors how to locate shrapnel in bodies using radiology and taught herself how to repair the equipment. She moved throughout facilities and battlegrounds including two bombsites, Furnes and Ypres, and Amiens. She received a military medal for her assistance in X-ray facilities in France and Belgium.
After the war, Irène returned to the Sorbonne in Paris to complete her second baccalaureate degree in mathematics and physics in 1918. Irène then went on to work as her mothers assistant, teaching radiology at the Radium Institute, which had been built by her parents. Her doctoral thesis was concerned with the alpha decay of polonium, the element discovered by her parents (along with radium) and named after Maries country of birth, Poland. Irène became a Doctor of Science in 1925.