Bayan yakin duniya na daya , Romania, wadda ta yi yaki tare da Entente, ta yi yaki da masu mulkin tsakiya, ta fadada yankinta sosai, ta hada da yankunan Transylvania, Bessarabia, da Bukovina, musamman sakamakon rashin kwanciyar hankali da aka haifar da rugujewar kasashen. Daulolin Austro- Hungarian da Rasha .Wannan ya kai ga cimma nasarar burin kishin kasa da aka dade ana yi na samar da babbar kasar Romania, kasa ta kasa wadda za ta hada dukkan kabilun Romania.Yayin da shekarun 1930 ke ci gaba, dimokuradiyyar Romania da ta riga ta girgiza a hankali ta tabarbare zuwa mulkin kama-karya.Kundin tsarin mulki na 1923 ya ba wa sarki ikon rusa majalisa da kuma kiran zabe yadda ya ga dama;Sakamakon haka, Romania za ta fuskanci gwamnatoci sama da 25 a cikin shekaru goma.Ƙarƙashin hujjar tabbatar da zaman lafiya a ƙasar, Sarki Carol II da ya ƙara yin shelar ‘mulkin kama-karya’ a shekara ta 1938. Sabon tsarin mulkin ya ƙunshi manufofin kamfanoni waɗanda sau da yawa kamar naFascist Italiya da Jamus na Nazi .^[85] A cikin layi daya da waɗannan ci gaba na cikin gida, matsin tattalin arziki da rashin ƙarfi na Franco - martanin Birtaniya ga mummunan manufofin ketare na Hitler ya sa Romania ta fara nisa daga Allies na Yamma kuma kusa da Axis.^[86]A lokacin bazara na shekara ta 1940 an yanke shawara kan rikicin yankuna da Romania, kuma ta rasa mafi yawan ƙasar Transylvania, wadda ta samu a yakin duniya na ɗaya. Shahararriyar gwamnatin Romania ta ragu, wanda ya ƙara ƙarfafa ƙungiyoyin Fasist da na soja, waɗanda a ƙarshe suka tayar da hankali. juyin mulkin da aka yi a watan Satumban 1940 wanda ya mayar da kasar mulkin kama-karya a karkashin Mareșal Ion Antonescu.Sabuwar gwamnatin ta shiga hukumance a hukumance a ranar 23 ga Nuwamba 1940. A matsayinta na memba na Axis, Romania ta shiga mamayewar Tarayyar Soviet (Operation Barbarossa) a ranar 22 ga Yuni 1941, tana ba da kayan aiki da mai ga Nazi Jamus tare da ba da ƙarin sojoji ga sojojin Soviet. Gabashin Gabas fiye da sauran kawayen Jamus a hade.Sojojin Romania sun taka rawa sosai a lokacin fada a Ukraine, Bessarabia, da yakin Stalingrad.Sojojin Romania ne ke da alhakin zalunci da kisan kiyashin da aka yi wa Yahudawa 260,000 a yankunan da Romania ke iko da su, ko da yake rabin Yahudawan da ke zaune a Romania ita kanta suka tsira daga yakin.^[87] Romania ta mallaki rundunar Axis mafi girma ta uku a Turai da kuma na huɗu mafi girma na sojojin Axis a duniya, a bayan manyan manyan Axis uku na Jamus,Japan , da Italiya.^[88] Bayan Satumba 1943 Armistice na Cassibile tsakanin Allies da Italiya, Romania ta zama na biyu axis Power a Turai.^[89]Ƙungiyoyin ƙawance sun jefa bama-bamai a Romania daga 1943 zuwa gaba, kuma sojojin Soviet na gaba sun mamaye ƙasar a cikin 1944. Babban goyon bayan da Romania ta shiga cikin yakin ya ragu, kuma gaban Jamus da Romania ya rushe a karkashin hare-haren Soviet.Sarki Mika'ilu na Romania ya jagoranci juyin mulkin da ya kori gwamnatin Antonescu (Agusta 1944) kuma ya sanya Romania a gefen Allies don ragowar yakin (an kashe Antonescu a watan Yuni 1946).A karkashin yarjejeniyar 1947 na Paris, Ƙungiyoyin ba su amince da Romania a matsayin ƙasa mai haɗin kai ba amma a maimakon haka sun yi amfani da kalmar "abokin Hitler na Jamus" ga duk masu karɓar sharuɗɗan yarjejeniyar.Kamar Finland, Romania ta biya dala miliyan 300 ga Tarayyar Soviet a matsayin diyya na yaki.Duk da haka, yarjejeniyar ta amince da cewa Romania ta sauya sheka a ranar 24 ga Agusta 1944, don haka "ta yi aiki a kan bukatun dukan Majalisar Dinkin Duniya".A matsayin lada, Arewacin Transylvania, an sake gane shi a matsayin wani muhimmin ɓangare na Romania, amma iyakar da Tarayyar Soviet da Bulgaria an daidaita su a jiharta a cikin Janairu 1941, maido da matsayin pre-Barbarossa (tare da banda daya).