Background: The waning vaccine immunity and emergence of new variants of SARS-CoV-2 led health authorities across the globe to administer booster doses (BDs) of the COVID-19 vaccine. Hence, the current study aimed to assess the COVID-19 vaccine booster hesitancy (VBH) amongst Pakistani healthcare professionals (HCPs). Methods: A nationwide survey-based study was carried out from April 2022 to May 2022. The online self-administered questionnaire was utilized to collect data regarding demographics (age, gender, marital status, profession, residential area, and province), COVID-19 infection history (infection history, onset, and clinical severity of disease), previous COVID-19 vaccination (type of vaccination and the number of doses), attitudes towards BDs (acceptance, rejection, and hesitancy), and psychological drivers of VBH (perceived effectiveness, vaccine safety, risk/benefit ratio, and vaccine type preference). We assessed the association between the dependent variable attitudes of study participants, regarding BDs and independent variables (demographics, COVID-19 infection history, previous COVID-19 vaccination, and psychological drivers of VBH), by using the Chi-square test/Fisher exact test. Results: Among the 1164 study participants, 51.4% were male, and 80.4% were medical professionals. The half of study participants (52.1%) agreed to take the COVID-19 vaccine BD or had already taken it, while the rest of them refused (34.7%) or hesitated (24.2%) to take it. These attitudes of the participants were significantly associated (p < 0.001) with psychological divers about the COVID-19 vaccine BD. Conclusion: This study revealed that Pakistani HCPs hesitant to take the COVID-19 vaccine BD had concerns about the safety, efficacy, and risk/benefits ratio of the vaccine’s BD. To eliminate the hesitancy, regarding BD in HCPs, certain educational strategies should be implemented by health authorities to address the concerns of HCPs.