Background: Pharmacists can play a role in enhancing treatment outcomes of autistic people, but they must possess sufficient knowledge and awareness of autism spectrum disorders (ASD). Current evidence is scant among Nigerian pharmacists. The objectives of this study were to: (1) Describe and compare Nigerian hospital and community pharmacists’ ASD knowledge, awareness, and perceptions; (2) Determine if there is a significant correlation between ASD knowledge, awareness, and perceptions; (3) Determine if demographic and practice-related factors are significantly related to pharmacists’ ASD awareness. Method: Hospital and community pharmacists were administered a self-report survey to assess ASD knowledge and awareness, as well as confidence in caring for autistic people, and perceived benefits of ASD training and care. Data were collected from August to December 2021 and analyzed using inferential and descriptive statistics. Cronbach’s alphas were used to assess reliability. Results: Of respondents, (Total N = 383; N = 201 hospital pharmacists from various states) and N = 182 community pharmacists in Lagos state) community pharmacists had significantly higher mean knowledge than hospital pharmacists (58.10% ± 19.00% vs 53.20% ± 20.10%; P = .016). Overall mean awareness score was 2.90 ± 0.80, with no significant difference between community and hospital pharmacists ( P = .096). Perception regarding ASD continuing education (CE) was strongly correlated with the perceived benefits of pharmacy services to autistic people in Nigeria ( r = .69; P < .0001). Additionally, awareness was positively correlated with knowledge ( r = .47, P < .0001) and perceived confidence in ASD medication counseling ( r = .54, P < .0001). Multivariate analysis revealed that being a hospital pharmacist, having courses on ASD during pharmacy degree programs, undergoing ASD CE, and having <5 years of practice experience were significantly ( P < 0.05) associated with higher ASD awareness. Conclusion: Respondents had suboptimal knowledge and awareness of ASD. Including ASD in the pharmacy curriculum and providing CE programs may help improve pharmacists’ ability to provide more optimal patient care services for autistic people.