Losick received his AB in Chemistry from Princeton University in 1965, and his PhD in biochemistry from Massachusetts Institute of Technology in 1969.

[6] Along with Daniel Kahne, Robert Lue, and Susan Mango, he teaches Life Sciences 1a, an introductory biology and chemistry course, which was the fourth largest lecture course taught at Harvard College in 2015.

[7] Losick's research interests include RNA polymerase, sigma factors, regulation of gene transcription, and bacterial development.

He is known for his studies of asymmetric division in Bacillus subtilis, which divides to form one endospore and one nurturing cell.

His research group has demonstrated that chromosomal DNA is recycled to form an electrostatic extracellular net in order to hold neighboring bacterial cells together.