Background and Objective: The coronavirus disease 2019 (COVID-19) pandemic had led to huge impact on society. The corresponding guidelines and legislation to limit social interaction, such as 2021 stay-at-home mandate for senior-high school level and below in Taiwan (“lockdown” restrictions), may have influence on health behaviors in various ways. This study aimed to examine whether 2021 COVID-19 lockdown in Taiwan is associated with the change in the use of cigarette and electronic cigarette (e-cigarette) among adolescents. Methods: This population-based pooled cross-sectional analysis study was conducted using the 2019 and 2021 Taiwan Global Youth Tobacco Survey. A total of 70,804 participants (aged 12 to18-years) was included. The outcome measures were cigarette and e-cigarette use. Multiple logistic regression was carried out to examine the association. Results: The prevalence of current cigarette use decreased from 6.2% in 2019 to 5.4% in 2021; nevertheless, the prevalence of current e-cigarette use increased from 4.2% in 2019 to 6.3% in 2021. Multivariate analysis showed that adolescents were less likely to report use cigarette in 2021 (aOR= 0.79, 95% CI: 0.66 to 0.95) than in 2019. In contrast, adolescents were more likely to report use e-cigarette in 2021 (aOR= 1.76, 95% CI: 1.38 to 2.25) than in 2019. Male, disposable income, parental smoking, peers smoking, household second-hand smoke exposure, parents’ education level and anti-smoke class were important factors for both the use of cigarette and e-cigarette use. Conclusions: We found the diverse influences of 2021 COVID-19 lockdown on adolescents’ tobacco product use. There was decreased use of cigarette yet increased use of vaping, though the sale of it remains illegal, among adolescents in Taiwan. Public health efforts to prevent and address the health harm from use of vaping or the potential switch from other tobacco products among adolescents is urgently needed.