Research suggests that whilst not more likely to offend, autistic people are overrepresented within the Criminal Justice System. To date, prevalence estimates are available only for male autistic offenders. Thus, this research aimed to provide the prison-reported rate of autistic female prisoners currently residing in the female prison estate in England. All 12 of the female prisons in England were contacted to request the following information: (1) the total number of autistic females; and (2) the total female prison population. Findings show an English female prison-reported rate of autism of 4.78% indicating that autism is approximately 13.7 times higher in female prisons compared to the general population. To the authors' knowledge, this is the first research article to focus exclusively on female autistic offenders. Further research is needed to understand the risk factors for offending, offender characteristics, offence types/patterns and autistic experience of the Criminal Justice System for female autistic offenders.