In present study, cacao oil-based organo-hydrogels (OHCOs) are synthesized to detect carcinoma antigen 125 (CA-125) in serum medium with electrochemical methods such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). OHCOs are prepared by the free radical polymerization reaction with agar, glycerol, and distinct ratios of cacao oil with glutaraldehyde (GA) crosslinker or methylene bisacrylamide (MBA) crosslinker. OHCOs are characterized via Fourier Transform Infrared Spec-troscopy (FT-IR), in different solvent environments and pHs. Electrochemical measurements are performed on OHCOs at the presence and absence of CA-125 antigen in serum medium. For the electrochemical sensor, two distinct linear ranges are determined as 0.00083-41.5 U/mL and 83.0-2075 U/mL. LOD and LOQ values are found as 0.34 mu U/mL and 1.01 mu U/mL, respectively. These results clearly show that OHCOs is a promising sensor material for the determination of CA-125 in human serum, sensitively.