Introduction: Early prediction of return of spontaneous circulation (ROSC) for cardiac arrest (CA) patients is a major challenge. This study’s goal was to investigate the value of the carboxyhemoglobin (COHb) and methemoglobin (MetHb) levels as a predictive marker for ROSC and prognostic marker for patients who achieve ROSC. Methods: A total of 241 adult patients (109 female, 132 male) diagnosed as non-traumatic CA were included in the study. The patients were divided into two groups based on whether they achieved ROSC. Complete blood count parameters, routine biochemistry measurements, coagulation parameters, and blood gas analysis, and cardiac markers values were compared between the groups. Results: COHb levels were significantly lower in the non-ROSC group (0.71 ± 0.57%) than in the ROSC group (0.95 ± 0.76%) and in the non-survival group (0.78 ± 0.53%) compared to the survivor group (1.45 ± 1.31%) (p =0.002, 0.022 respectively). There was no significant difference between the ROSC and non-ROSC groups and survivor group and non-survivor groups in terms of MetHb levels (p = 0.769 and 0.668, respectively). Conclusions: COHb levels in the blood gas analysis at the time of admission could be used as a predictive marker for ROSC and prognostic marker for the patients who achieved ROSC.