As a rare element with no known natural biological function, rhodium has a limited history in biological chemistry and chemical biology. However, rhodium complexes have unique structure and reactivity attributes, and chemists have increasingly used these attributes to probe and perturb living systems. This brief review focuses on recent advances in the use of rhodium complexes in biological contexts, including medicinal chemistry, protein science, and chemical biology. In particular, we highlight both structure- and reactivity-driven approaches to biological probes and discuss how coordination environment affects molecular properties in a biological environment.