Jokic is expected to begin training with Forest immediately, the report states.
So who is the latest new face at the City Ground? Here are five facts about the player...
1) Jokic, 29, is a left-back who will replace Dani Pinillos, who suffered an ACL tear last month, but has made only two La Liga appearances this season, but has played four times in the Europa League.
2) He has 73 international caps for Slovenia, scoring once - against Qatar, and has played against England.
3) As well as in Spain and in his homeland, Jokic has also played in France with Sochaux and Italy with Chievo.
4) Whoscored.com list his strengths as his crossing, winning aeriel duels, tackling, and concentration.
5) He played only seven league games in 2014/15, missing almost the entire campaign through injury.