Career
Club Mitrović made his professional football debut for HNK Cibalia on 25 February 2012, coming on as a substitute. He made three further appearances that season. In the 12/13 HNL season, Matej played in all 33 of the league games that season, the majority of those appearances as a center back but also played left and right full back.
In September 2013, he signed for Rijeka from Cibalia on a two-year contract, with the possibility of additional two years.
The fee was rumored to be €500,000. The next season he started to get more playing time and also got his first senior national team call-up, when Niko Kovac called him up as an injury replacement for Gordon Schildenfeld.
Mitrović made his Croatia debut in a friendly against Argentina on 12 November 2014.