Background <p>Obtaining a diagnosis of endometriosis is often a long and involved journey. Little specific information exists about this journey for young people. This qualitative systematic review and thematic synthesis aimed to describe help-seeking experiences for young people who have been diagnosed with endometriosis, with attention to their needs, priorities, and relationships.</p> Methods <p>A systematic search was conducted of MEDLINE, Embase, PsycINFO, CINAHL, SocINDEX, Google Scholar, and ProQuest Dissertations and Theses on 18/12/2024. This combined the term “endometriosis” with variants of the concept “help-seeking”. Eligible articles reported the first-person perspectives of young people aged 10–24 years who were diagnosed with endometriosis. Quality assessment was conducted using the QualSyst tool. Thematic synthesis was used to construct themes.</p> Results <p>A total of 5,287 unique titles were assessed. 29 qualitative or mixed-methods studies (reported in 35 articles) met inclusion. Five analytical themes were generated: (1) Distinguishing ‘normal’ from ‘abnormal’ menstruation is difficult for young people, (2) Young people anticipate unhelpful responses, (3) Healthcare encounters aren’t tailored to young people, (4) Invalidation has disruptive consequences, and (5) Young people need acknowledgment and resources.</p> Conclusions <p>Validating relationships and age-relevant information and resources are needed to improve the help-seeking experiences of young people with endometriosis. Healthcare professionals must also ensure services are tailored to young people’s life stage and concerns.</p> Trial registration <p>Prospero ID CRD42024575314.</p>