Multiwalled carbon nanotubes (MWCNTs) enhance osteoblast (bone-forming cell) calcium deposition compared to currently implanted materials (such as titanium). In this study, MWCNTs were grown out of nanopores anodized on titanium (MWCNT–Ti). The electrochemical responses of MWCNT–Ti were investigated in an attempt to ascertain if MWCNT–Ti can serve as novel in situ sensors of bone formation. For this purpose, MWCNT–Ti was subjected to a ferri/ferrocyanide redox couple and its electrochemical behavior measured. Cyclic voltammograms (CVs) showed an enhanced redox potential for the MWCNT–Ti. These redox signals were superior to that obtained with bare unmodified Ti, which did not sense either oxidation or reduction peaks in the CVs. A further objective of this study was to investigate the redox reactions of MWCNT–Ti in a solution of extracellular components secreted by osteoblasts in vitro. It was found that MWCNT–Ti exhibited well-defined and persistent CVs, similar to the ferri/ferrocyanide redox reaction. The higher electrodic performance and electrocatalytic activity of the MWCNT–Ti compared to the bare titanium observed in this study were likely due to the fact that MWCNTs enhanced direct electron transfer and facilitated double-layer effects, leading to a strong redox signal. Thus these results encourage the further study and modification of MWCNT–Ti to sense new bone growth in situ next to orthopedic implants and perhaps monitor other events (such as infection and/or harmful scar tissue formation) to improve the current clinical diagnosis of orthopedic implants.