Employers’ knowledge and awareness about autism can be a key barrier to autistic people obtaining employment. The current study evaluated the efficacy of an online autism training programme, Understanding Autism in the Workplace, in changing employers’ autism knowledge and commitment to inclusion in the workplace. Employers (N = 129) from 22 organisations in the UK completed the training with an autistic (n = 45) or non-autistic (n = 84) trainer and completed surveys measuring (a) autism knowledge and (b) commitment to inclusion in the workplace, before and after the training. Results showed that at a group-level, autism knowledge and commitment to inclusion in the workplace improved from before training to after training for all participants with an autistic and a non-autistic trainer (this latter result may be attributable to the training being co-designed by autistic people). At an individual-level, however, a minority of participants showed a significant increase in autism knowledge (10.1%), and commitment to inclusion in the workplace (5.8%), suggesting autism training was more effective for some participants than others. Autism training should not be the sole initiative to address barriers to employment for autistic people, but should be part of a broader package of support for employers.