Early detection of cancer is the key to improve survival rates of cancer patients. In addition to this, another point of concern is high specificity or selectivity of diagnostic assay or device to avoid false positive/negative predictions. Here, we present the evaluation of biosensing potential of computationally predicted aptamer for cancer antigen 125 (CA125). The aptamer was predicted using computational tools like PPAI, HDOCK and pyDOCKDNA. The lead aptamers were then screened for their binding affinity towards other cancer biomarkers present in blood. The aptamer sensor was fabricated by immobilizing predicted aptamer onto gold nanoparticles modified electrode surface. The developed aptasensor displayed dynamic range from 10 to 100 ng/mL and lower limit of detection (LLOD) of 0.599 fg/mL. The sensitivity of aptasensor developed using proposed aptamer was 61.361 µA/µg/mL/cm2. The developed aptasensor holds promise as prognostic tool for ovarian cancer diagnosis.