Cynhaliwyd Diwrnod Rhyngwladol cyntaf y Menywod ym mis Mawrth 1911, pan ddaeth menywod a dynion ynghyd i drafod yr angen i fenywod gael hawliau sylfaenol – yr hawl i bleidleisio, yr hawl i weithio, yr hawl i ddweud eu dweud yn gyhoeddus, a’r hawl i gyflog cyfartal. Fel dathliad blynyddol, mae Diwrnod Rhyngwladol y Menywod yn cynnig y cyfle i ystyried y flwyddyn flaenorol, a rhoi sylw i waith sydd wedi'i wneud i wella cydraddoldeb rhwng y rhywiau.
The first International Women’s Day was held in March 1911 when women and men came together to talk about the need for women to have basic rights afforded to them, the right to vote, the right to work, the right to speak out in public and the right to equal pay. As an annual celebration, International Women’s Day provides the opportunity to reflect on the previous year and  highlight the work which has taken place to advance gender equality.