In this study, Ti6Al7Nb and Ti29Nb13Ta4.6Zr (TNTZ) alloys coated with graphene oxide (GO) and serotonin (Ser) by electrophoretic deposition (EPD) technique were evaluated for possible usage as an orthopedic implant in terms of their in-vitro corrosion response, biocompatibility, and wettability. In-vitro corrosion analyses were carried out to determine the electrochemical response of the coatings in Hanks’ solution (named as SBF) at body temperature (37 °C). Biocompatibility of the coated materials was evaluated by direct contact method using normal mouse calvarial preosteoblast cell line (MC3T3-E1 Subclone 4). To this purpose, cytotoxic effect and cell proliferation rate were evaluated. The wettability test was performed using static contact angle method (sessile drop technique). The results showed that only GO and GO+Ser coatings had a negative effect on the corrosion resistance of TNTZ alloy. However, the Icorr value of the GO+Ser coatings improved almost 2 and 4 times compared to only GO coated Ti6Al7Nb and uncoated Ti6Al7Nb, respectively. GO+Ser coating made the substrates more hydrophilic, making the surface more suitable for protein adsorption and cell adhesion. Obtained results showed that GO+Ser coated Ti6Al7Nb was more favorable to osteoblast survival (106% viability after 24-h incubation), adhesion and proliferation (almost 6 times faster after 3 days of incubation) compared to only GO coated Ti6Al7Nb (87% viability). Confocal microscope analysis confirmed WST-8 cytotoxicity test results and non-cytotoxicity of the modified surfaces. The GO+Ser coated Ti6Al7Nb possesses better biomedical potential than GO coated Ti6Al7Nb.