Mijailović is a product of Metalac's youth school, and was a member of generation which made promotion to the best level Serbian youth league in 2014.[2]
He made his debut for Metalac in 2012–13 season. Next season he made 1 league appearance too,[3] but he was sitting on the bench several times. He also played 1 cup match against Partizan,[4] and one play-off match for the Serbian SuperLiga, against Rad.[5] Second match he started on the field, but complained of a headache from the tear gas that caused the match later was interrupted.[6] After youth career, he left Metalac and joined local Zone league club Takovo,[7] but he returned in his home club after six months and signed four-year contract at the beginning of 2015.[8] He made his SuperLiga debut in the 7th fixture of 2015–16, against Spartak Subotica.[9] In summer 2016, Mijailović moved on one-year loan to Serbian First League side Kolubara.[10]
^"Stvarno najbolji!". FK Metalac official website (in Serbian). 24 June 2015. Archived from the original on 4 March 2016. Retrieved 23 August 2015.
^"Mladenović srušio Radnik". FK Metalac official website (in Serbian). 4 November 2013. Archived from the original on 24 September 2015. Retrieved 27 August 2015.
^"7.Kolo: Spartak - Metalac". Serbian SuperLiga official website (in Serbian). 22 August 2015. Archived from the original on 22 August 2015. Retrieved 23 August 2015.