Rubuta ci gaba don wannan sakin layi - Bayan Yaƙin Opium na Farko da kafa Hong Kong, Macau ya rasa rawar da yake takawa a matsayin babbar tashar jiragen ruwa. Ƙarƙashin wuta da ƙona turare, da kuma sarrafa shayi da taba, muhimman sana'o'i ne a cikin mulkin mallaka a wannan lokacin. Kasar Portugal ta sami damar cin gajiyar raunin kasar Sin bayan yakin da kuma tabbatar da ikonta; Gwamnan Macau ya fara kin biyan kasar Sin kudin haya na shekara-shekara don mulkin mallaka a cikin shekarun 1840, kuma ya hade Taipa da Coloane, a cikin 1851 da 1864 bi da bi. Portugal kuma ta mamaye Lapa da Montanha da ke kusa, amma za a mayar da su zuwa China a shekara ta 1887, lokacin da aka ba da haƙƙin mallaka na har abada a kan Macau a cikin Yarjejeniyar Peking ta Sin da Fotigal. Wannan yarjejeniya kuma ta hana Portugal daga barin Macau ba tare da amincewar kasar Sin ba. Duk da rikice-rikice na lokaci-lokaci tsakanin hukumomin Cantonese da gwamnatin mulkin mallaka, matsayin Macau bai canza ba ta hanyar juyin juya halin jamhuriya na duka Fotigal a 1910
da kuma China a shekarar 1911. Kuomintang ta kara tabbatar da ikon mallakar Fotigal a Macau lokacin da aka sake tattauna yarjejeniyar Peking a 1928.