Siniša Krajač was born in Zagreb on 13 August 1968. He won a master's degree in kinesiology (teacher of physical education and health) at the Faculty of Kinesiology, University of Zagreb. He speaks English.
As a student, he worked at the football school of the Lokomotiva Football Club in which his sports career also developed under the leadership of the legendary coach. Ilija Lončarević.
In 2001, after having worked at the Ministry of Defence of the Republic of Croatia, more precisely in the Sports Depatrment of Armed Forces, he began working in the Croatian Olympic Committee. His previous job in the Ministry of Defence was Head of Verifictiion and Analytics Department at the Security and Informatioin Service. During the 2nd Military World Games in Zagreb, he headed the water sports group.
During two decades of working in the Croatian Olympic Committee, he occupied several important positions: Acting Director of the National Sports Federations Programme Office (2004-2007); Head of the Development Programmes Office, two terms of office (2001-2004 and 2007-2010); prior to the current position, he was Assistant to the Secretary General for Local Sport Programme.
He participated in the homeland war and is a founder of the MIG voluntary student armed units that was later added to the ALFA Special Police.
As a spare and active commando, ALFA member from 1991 to 1993, he fought at many Croatian battlefields.
After the earthquake in Banovina in late 2020, he organized together with the local community representatives help for athletes, their families and sports associations from this region and after the involvement of the IOC and EOC, he deserves credit for the first prefabricated multi-sports hall in Petrinja. Siniša Krajač is the sixth Secretary General in 32 years of the Croatian Olympic Committee. His term of office began on 10 May 2021.