Thailand's first wave of COVID-19 in March 2020 was triggered from boxing events and nightclubs in Bangkok, which spread to 68 provinces. The nation responded rapidly with strong public health and social measures on 26 March 2020. Contact tracing was performed by over 1000 surveillance and rapid response teams with support from 1.1 million village health volunteers to identify, isolate and quarantine cases.Thailand implemented social measures in April 2020 including a full-scale national lockdown, curfews and 14-day mandatory quarantine for international travellers. With a strong health system infrastructure, people's adherence to social measures and a whole-of-government approach, the first wave recorded only 3042 cases and 57 deaths with 1.46% case fatality rate. Economic activities were resumed on 1 May 2020 until the end of the year. On 17 December 2020, a second wave was carried by undocumented migrants who were not captured by the quarantine system. As the total lockdown earlier led to serious negative economic impact, the government employed a targeted strategy, locking down specific areas and employing active case finding. Essential resources including case finding teams, clinicians and medicine were mobilised.With synergistic multisectoral efforts involving health, non-health and private sector, the outbreak was contained in February 2021. Total cases were seven times higher than the first wave, however, early admission and treatment resulted in 0.11% case fatality rate. In conclusion, experiences of responding to the first wave informed the second wave response with targeted locking down of affected localities and active case findings in affected sites.