Post rollout safety for the coronavirus disease vaccines is crucial and recommended. To explore the early solicited adverse events (AE) following BNT162b2 mRNA vaccination in Saudi Arabia, we distributed an online survey to adults vaccinated with BNT162b2 over the first week of June 2021, to collect data on first (V1), second doses (V2), symptoms, severity, and outcome after an informed consent was obtained. We recruited 3639 BNT162b2 vaccinated individuals, of which one-third had received two doses, 63.3% were female, 77% were healthy, and 89% had 18–55 years of age, while only 9.8% had a history of allergy. Overall, 50.3% had any AEs after any dose, especially those younger than 55 years of age, female, history of comorbidity, and when adjusted for age and gender, lung or cardiovascular diseases. Overall, the most common AE were pain at the injection site (44%), tiredness (39%), or body ache (31%). Compared to V1, a higher rate of post-V2 systemic AE (36% vs. 51%). Most AEs started very early (within 3 days), and rarely delayed in recovery (>2 weeks). Anti-pyretic was the most commonly used (51.7%), a third of which was unnecessary. Only 1.7% required hospital admission. By multivariate analysis, predictors for admission were the presence of lung or immunocompromising diseases. In conclusion, common AEs after BNT162b2 in the real world were generally mild, self-limiting, higher after the second dose, and largely mimicking that reported in clinical trials. The causality of these AE and the persistence of post-vaccination symptoms needs to be investigated further.