Dubos was born in Saint Brice, France, and graduated in agricultural sciences from the National Agronomy Institute in 1921. After a period with the International Institute of Agriculture in Rome as assistant editor, he emigrated to America in 1924.

Dubos was awarded his PhD in 1927 from Rutgers University for research on soil microorganisms, continuing his work in this field at the Rockefeller Institute for Medical Research. Reports that soil microorganisms produce antibacterial substances particularly interested him and in 1939 he isolated a substance from Bacillus brevis that he named tyrothricin. This is effective against many types of bacteria but unfortunately also kills red blood cells and its medical use is therefore limited. However, the discovery stimulated such workers as Selman Waksman and Benjamin Duggar to search for useful antibiotics and led to the discovery of the tetracyclines. He won the 1969 Pulitzer Prize for his book So Human an Animal.