The purpose of this study was to find out the effect of migration on the livelihood security of the estate sector in Sri Lanka as none of the other reported studies covered livelihood security issues with respect to whole country. Data for the study come from the Household Income and Expenditure Survey (2016) conducted by the Department of Census and Statistics of Sri Lanka. A composite index approach was applied to construct the livelihood security index which was formulated based on economic security, food security, education security, health security, and habitat security. The propensity score matching (PSM) method was employed to illustrate the impact of migration and remittances on livelihood security and its outcomes, while addressing the self-selection problem. Average treatment effect (ATT) results showed significant differences in ATT effect of remittances on economic security, food security, and education security, and no significant difference in ATT of receiving remittances with health security and habitat security. Remittance receiving households consisted of high education security and health security than the non-remittance-receiving households with low economic security, food security, and habitat security. The study concludes that migration and remittances affect livelihood security of estate sector households positively.