Graphitic nanomaterials, which possess unique optical properties, have attracted significant attention in biochemical sensing. Herein, we summarize and discuss recent progress of such materials as optical probes, photothermal materials and signal transduction substrates for biosensing applications. The most attractive optical property of graphitic nanomaterials is their strong and unique Raman signals. As a Raman probe, these nanomaterials have remarkable applications, especially in detecting complex biological samples, quantitative surface enhanced Raman scattering (SERS) detection and detection under extreme conditions. Besides Raman, the unique intrinsic fluorescence emission of single-walled carbon nanotubes (SWNTs) in the long wavelength and second near-infrared window (NIR-II window, 1000-1700 nm) has facilitated deep-tissue high-resolution fluorescence imaging in vivo. Additionally, graphitic nanomaterials have efficient photothermal conversion capability. Together with the large surface area, graphitic nanomaterials are used in photothermal synergy therapy for cancer treatment. Furthermore, because of their particular physical and chemical properties, graphitic nanomaterials are established as an efficient signal transduction substrate, which can quench an excited chromophore and photosensitizer, showing high selectivity and sensitivity in biosensing and nanomedicine.