Rubuta ci gaba don wannan sakin layi - A lokacin yakin duniya na farko, Maček ya kasance jami'in ajiya. Saboda haka, an tattara shi cikin Rundunar 'Yan Kasa ta 25 na Sojojin Austro-Hungary a matsayin kwamandan kamfanin na 3 a ranar 27 ga Yuli, 1914. Maček ya halarci yakin Serbia kuma ya ji rauni a yakin Kolubara
yayin da suke haye kogin Kolubara a watan Nuwamba. Bayan ya dawo daga asibiti a Novi Sad zuwa Zagreb kafin Kirsimeti, an yi masa ado don jaruntaka kuma an ba shi mukamin laftanan. Saboda astigmatism dinsa, an ayyana shi mara cancanta don yin aiki a fagen yaƙi, kuma an nada shi kwamandan wani kamfanin injiniya, wanda ya ƙunshi 'yan Poland da Ukrainians. Kamfaninsa ya shirya kare Budapest, kuma daga baya tashar jiragen ruwa ta Austrian-Hungary a Pula, inda ya yi aiki har zuwa kaka 1916. Daga 15 ga Oktoba 1916 zuwa 15 ga Maris 1917 ya yi aiki a cikin sojojin mamaye a Albania.