ObjectivesBody image disturbance is prevalent in people with endometriosis. This study aimed to explore the feasibility, acceptability and preliminary efficacy of the My Changed Body (MyCB) writing activity for body image in people with endometriosis.DesignTwo‐arm randomized controlled pilot and feasibility study.MethodsAustralian adults living with endometriosis who identified as having had a negative endometriosis‐related body image experience were recruited online through Endometriosis Australia. Participants completed a baseline survey capturing demographic and health data before being randomized into the MyCB or control writing conditions. Additional assessment was administered post‐activity and at 1‐week follow‐up.ResultsA total of 82 participants were recruited and randomized (Mage = 32 years, SD = 7.8). MyCB participants were less likely to complete the writing tasks compared to the control group (51% vs. 83%); MyCB completers had lower self‐compassion and quality of life, and higher psychological distress, compared to those who dropped out. The MyCB activity received good satisfaction rates (47%–87%). However, there was significant drop‐out in the MyCB group (n = 4 vs. 13 at 1‐week follow‐up). Limited‐efficacy testing showed an increase in the self‐compassion self‐identification for the MyCB group.ConclusionsThe MyCB writing activity may be feasible for people with endometriosis. A future larger trial will benefit from several methodology changes to enhance recruitment and retention.Trial RegistrationAustralian and New Zealand Clinical Trial Registry ACTRN12622000496718; Date: 29/3/2022; retrospectively registered.