Biological redox is a promising indicator of life for NASA’s future exploration missions of Ocean Worlds. Electrochemical sensors are valuable tools for detecting these biological redox signatures on Earth; however their application to planetary exploration has been limited. All forms of life on Earth contain cellular machinery that can transform and regulate chemical energy through electron transfer pathways performed by key classes of naturally-occurring biological redox molecules including flavins, nicotinamides, porphyrins, and quinones. In this study, we use electrochemical techniques to measure these redox molecules in a synthetic seawater solution. This study also appropriates an electrochemical immunoassay technique for alkaline phosphatase detection, where comparison of the unique redox signatures of enzyme substrates and products reflect enzymatic activity. Naturally-occurring redox molecules exhibit unique redox signatures with anodic peak locations indicative of their respective molecular class. In this work, we report measured limits of detection as low as 10 nM and 3.13 aM for naturally-occurring redox molecules and alkaline phosphatase respectively. Overall, the findings of this study demonstrate that electrochemical sensors are effective tools for life detection applications for future Ocean Worlds missions.