Synchronous human papillomavirus‐independent gastric‐type adenocarcinoma in situ affecting both cervical and vaginal epithelium constitutes an ultrarare preinvasive disease. The diagnostic complexity arises from asymptomatic presentation and skip lesions that obscure the true extent of the disease. We report the case of a 26‐year‐old woman diagnosed with atypical glandular cells during routine cervical cancer screening. Sequential conizations consistently demonstrated gastric‐type adenocarcinoma in situ with persistently positive surgical margins. Post‐conization colposcopic assessment and histopathology revealed extensive multifocal disease involving residual cervix and vaginum. Considering the substantial disease burden and potential for occult invasion, surgical intervention was undertaken, including type B1 radical hysterectomy, bilateral salpingectomy, bilateral ovarian tissue cryopreservation, total vaginectomy, and vaginal reconstruction. At 20 months of follow‐up, the patient remains completely disease‐free with no evidence of recurrence.