Chicago Fire as a Designated Player for a reported transfer fee of $3 million from Legia Warsaw on 20 December 2016 on a three-year deal worth reportedly $1.9 million per year, per MLS Players Union documents. Speaking on the transfer, in a press release by the club, Fire GM Nelson Rodriguez stated "Through this transfer, we have secured a champion in his prime, and one of the most prolific goal scorers in Europe over the last few years". Fire coach Veljko Paunović noted his awareness of Nikolić from an early age from his time in Serbia. In an article published by the Fire Paunović praised Nikolić's skillset: "His quality is scoring goals and assisting, but then he's a man that can participate in both phases of team play," Paunovic said. "He's very good in all phases of the game. Defensively, he helps the team to recover the ball as soon as possible in order that we can control the game and create opportunities for our team to win. Sometimes he will benefit from team play and he will be just the executor, but sometimes he's capable of creating his own situations in the game, the opportunities 1v1, and scoring his own goals." 2017 season Nikolić's high career strike-rate continued with the Fire, where he became an instant success - leading the league in scoring and acquiring numerous accolades through the first half of the season, and ultimately winning the 2017 MLS Golden Boot. His first goal for the club came in the Fire's 2017 home opener against Real Salt Lake, in which he scored an unassisted effort in the 11th minute. Nikolić was named to the MLS Team of the Week in week 7 alongside fellow Fire forward Luis Solignac. He was additionally selected as MLS player of the week in week 7. He was once again chosen for team of the week in week 11 for his brace in Chicago's 4–1 win against the reigning MLS Cup champion Seattle Sounders. With 10 goals through the first 11 games of the season, Nikolić led the league in scoring. With his brace against the Colorado Rapids on 16 May, he became the first Fire player to score in four straight games since Mike Magee in 2013. This brace once again earned him MLS Team of the Week honors. After week 15 Nikolić continued to lead the league in scoring, with 12