Salmonella Typhimurium and Campylobacter jejuni are major foodborne pathogens that persist along the poultry processing line, posing public health risks and significant economic burdens. Chlorine is commonly used in spin chill tanks to wash poultry carcasses and mitigate carcass contamination during processing. Although chlorine concentrations vary across the poultry industry, the prevalence of foodborne pathogens in poultry remains significant. This study determined the chlorine resistance in S. Typhimurium and C. jejuni isolated from caecal, neck skin, carcass washings, and environmental samples using minimum inhibitory concentration/minimum bactericidal concentration assays. Regardless of the chlorine concentration in the chill tank, higher tolerance levels were observed in S. Typhimurium and C. jejuni isolated from carcass washings. The lowest tolerance level was observed in environmental isolates that had not been previously exposed to chlorine. Notably, 60% of carcass-washing C. jejuni pre-exposed to 40 ppm chlorine in the chill tank showed a higher tolerance level of 160 ppm chlorine, while 80% of S. Typhimurium pre-exposed to 20 ppm showed an 80 ppm tolerance level. Notably, 94.1% of S. Typhimurium and 80% of C. jejuni, isolated from the carcass washing, were resistant to chlorine in the present study. Similarly, the highest resuscitation rates were detected in the same isolates at 52.4% and 58.5%, respectively. The lowest resistance and the highest resuscitation rate were observed in the environmental isolates. Pre-exposure to chlorine during processing has increased the chlorine resistance of both pathogens. The observed resistance may limit the effectiveness of mitigation protocols that rely on concentration adjustments in the chill tank. Therefore, an alternative chemical with a novel disinfection protocol is crucial to mitigate bacterial contamination in poultry processing.