The Cottagers swooped to sign Newcastle striker Mitrovic on loan in the final hours of the transfer window after a move to Anderlecht collapsed.
“He's a strong, young, quality player, and I believe he can be important for the team," Jokanovic said.
“From another side I also believe he can push my strikers to work harder still and fight for a place in the team. I need competition between my players to be ready to compete against the opposition.
“We tried to create a good atmosphere for work, and this can help us fight for important targets."