Salinity is a major threat to global rice production. This study investigated salinity stress tolerance mechanisms, in vitro in six rice genotypes – TRY 4, TRY 3, CR 1009 Sub 1, CO 53, CO 55 and ADT 37. Callus induction frequency, relative growth rate, regeneration percentage and biochemical markers (proline, catalase, superoxide dismutase and peroxidase) were analysed under 0-100 mM NaCl treatments. Callus induction frequency, growth rate and regeneration declined with increasing salinity in all genotypes, however TRY 3 and TRY 4 maintained comparatively higher growth and regeneration up to 100 mM NaCl indicating superior tolerance. Proline, catalase, superoxide dismutase and peroxidase levels increased with salinity levels in most genotypes as protective responses. TRY3 and TRY4 exhibited highest increases in these biochemical markers, conferring tolerance against salinity-induced osmotic and oxidative stresses. ADT 37 and CR 1009 Sub 1 showed reduced growth parameters and lower biochemical defence responses, marking them as salt-sensitive. Principal component analysis clearly distinguished control and salt-treated groups based on measured parameters. Overall, the study revealed varying salinity tolerance mechanisms in rice genotypes, with TRY 3 and TRY 4 as promising salinity-tolerant lines. These findings provide insights to aid breeding salt-tolerant rice varieties to ensure food security against rising soil salinity.