The COVID-19 caused a world pandemic, posing a huge threat to global health. Widespread vaccination is the most effective way to control the pandemic. Vaccination with the third dose of the COVID-19 vaccine is currently underway. We aimed to determine the attitude of adolescents toward the third dose of COVID-19 vaccine.

A structured questionnaire was administered between 16 August and 28 October 2021 among adolescents aged 12–17 years in three provinces of eastern region of China based on convenience sampling. The questionnaire was specifically developed to assess the adolescents’ attitude toward and willingness to accept a third dose of the COVID-19 vaccine.

In total, 94.3% (1742/1847) of the adolescents intended to accept the third dose of the COVID-19 vaccine. Age between 15–17 years, no worry about vaccine safety, confidence for vaccine effectiveness, and supporting opinion from parents were independently associated with acceptance of the third dose (p < 0.05).

It is necessary for governments and school administrators to raise adolescents’ and parents’ awareness of the benefits and safety of the third dose of vaccination, which should be effective to increase the vaccination coverage among adolescents.