A second COVID-19 vaccine booster dose is effective and safe for older adults. This study investigated hesitancy to take up a second COVID-19 vaccine booster dose and its determinants among older adults in Hong Kong. Participants were Chinese-speaking community-dwelling adults aged 65 years or above. Telephone numbers were randomly selected from up-to-date telephone directories. A total of 370 participants completed the telephone survey. Logistic regression models were fitted for data analysis. Among the participants, half (52.4%) were hesitant to receive the second COVID-19 vaccine booster dose. After adjustment for significant background characteristics, perceived benefits (AOR: 0.50, 95%CI: 0.42, 0.60), cues to action (AOR: 0.39, 95%CI: 0.30, 0.52), and perceived self-efficacy (AOR: 0.37, 95%CI: 0.21, 0.66) of receiving the second booster dose were associated with lower vaccine hesitancy. Perceived barriers (AOR: 1.23, 95%CI: 1.12, 1.34) and vaccine fatigue (tired of receiving repeated COVID-19 vaccination) (AOR: 1.90, 95%CI: 1.52, 2.38) were associated with higher vaccine hesitancy. Level of hesitancy to receive the second booster dose was high among older adults in Hong Kong. Health authorities should address vaccine fatigue and modify perceptions related to the second booster dose.