The 2024 WHO guidelines for chronic hepatitis B (CHB) aim to expand and simplify treatment eligibility. We aimed to estimate treatment eligibility and uptake according to country-specific guidelines and evaluate treatment expansion based on the WHO guidelines. Treatment-na & iuml;ve CHB patients from Argentina, Brazil, Chile and Uruguay referred to evaluation between January 2010 and June 2024 were retrospectively included. Treatment candidacy was evaluated according to both country-specific and WHO guidelines. A total of 719 patients with CHB, treatment na & iuml;ve, were included (67.1% male; median age: 50.4 years; HBeAg-positive: 36.3%). The median HBV-DNA level was 43,000 (IQR 633-110,000,000) IU/mL, median ALT was 41 (IQR 23-99) U/L, 47.0% had an APRI > 0.5 and 21.1% had cirrhosis. According to country-specific guidelines, 56.9% (95% CI: 53.2-60.5) met the criteria for treatment. Antiviral treatment was initiated in 84.3% of eligible patients. The proportion of patients meeting treatment criteria under the WHO guidelines increased to 67.3% (95% CI: 63.8-70.6), resulting in a 10.4% (95% CI: 8.1-12.8) increase in treatment candidacy. Treatment expansion was significantly higher in women (15.2%; 95% CI: 10.2-20.1) than in men (8.1%; 95% CI: 5.4-10.7). According to WHO guidelines, a considerable proportion of CHB patients who do not meet country-specific criteria are eligible for antiviral therapy. Implementing WHO criteria can enhance treatment rates and advance efforts toward CHB elimination.