The coronavirus disease 2019 (COVID-19) pandemic has deteriorated the healthcare system and economy worldwide. Globally, by making the primary vaccination against the coronavirus necessary, the surge in cases waned, but as the effects of this vaccination decreased after some time, to prevent another pandemic, vaccination was still necessary. As a result, receiving a COVID-19 booster shot can boost immunity against the coronavirus. This study aimed to assess knowledge of COVID-19 booster vaccines in Pakistan among the general public and understand the factors affecting the vaccination process in the state. In this cross-sectional study, non-probability convenience sampling was done. Its physical data collection was conducted in September 2022 in a tertiary care hospital in Karachi, Pakistan. Data were collected from 384 individuals who visited the hospital with consent before filling out the questionnaire. The mean age of respondents was 35.81 (standard deviation (SD) = ±13.006), and 98.7% of individuals were primarily vaccinated for COVID-19, but out of these, only 60.1% received the booster jab. The most commonly reported side effects of primary doses of COVID-19 and its booster were pain at the injection site, fatigue, and fever, but these effects did not appear to have as much of an impact on the vaccination process as education did. The results are evident that out of primarily vaccinated individuals against COVID-19, 40.16% are reluctant to receive its booster. Therefore, it is essential to create awareness among the masses about vaccination and its importance.