U-Oliver Reginald Tambo wazalwa ngomhlaka-27 kuMfumfu ngonyaka ka-1917 endaweni ebizwa ngokuthi iNkantolo edolobheni laseBizana;ePondoland eseyaziwa ngokuthi y i-Eastern Cape. Lendawo uTambo wavelela kuyo kwakusemapulazini.Ubaba wakhe, uMzimeni Tambo, wayeyindodana yomunini pulazi nomsizi wesitolo esisasiseduze nakubo. Ubaba uMzimeni wayenamakhosikazi amane nezingane eziyishumi, Bonke babengafundile. Umama ka-Oliver wayeyinkosikazi yesithathu, igama lakhe kwakungu Julia Tambo. Babevela emndenini ozimele.Izingane zikababa wakhe kwakumele zibe nemfundo enhle. Wafunda e-Angelican and Methodist Missionary School nase Holly Cross Missionary School nobhuti wakhe. Ngemuva kweminyaka emihlanu e-Holy Cross, uTambo wenza kahle ezifundweni zakhe wadlulela eSt Peter, eGoli. UTambo wenza iziqu ngonyaka ka-1938 njengomunye wabafundi abaphambili. Ngemuva kwalokho, uTambo wangeniswa eNyuvesi yaseFort Hare kodwa ngo-1940 yena kanye nabanye abaningana kuhlanganisa uNelson Mandela, waxoshwa ngenxa yokubamba iqhaza esitelekeni sabafundi. Ngonyaka ka-1942, uTambo wabuyela esikoleni ayekade efunda kuso esikoleni samazinga aphakeme eGoli ukuyofundisa izifundo zesayensi nezibalo. Ngonyaka ka-1943, uTambo, uMandela kanye noWalter Sisulu basungula uphiko lwentsha lwe-ANC, lapho uTambo eba nguNobhala wabo wokuqala kazwelonke futhi waba yilungu lesigungu Sikazwelonke ngo-1948.