In the league, Napoli set a new club record for points in a single Serie A season, finishing with 91, though this would only be good enough for 2nd place behind champions Juventus, with 95. Dries Mertens was once again the club's top league goalscorer, albeit with ten fewer goals than the previous season; he scored 18 in Serie A and 22 in all competitions. In the Coppa Italia Napoli were eliminated in the quarter-finals by Atalanta. In the Champions League, Napoli had first to navigate through the play-off round, successfully eliminating French club Nice with 2–0 wins in both legs, 4–0 on aggregate. However, having been drawn into a group with English club Manchester City, Ukrainian club Shakhtar Donetsk, and Dutch club Feyenoord, Napoli finished a disappointing third, with four defeats and only two victories. As a result Napoli dropped down to the round of 32 of the Europa League, once again experiencing European disappointment as they were eliminated on away goals after drawing 3–3 across two legs with German club RB Leipzig.
This was Maurizio Sarri's third and final season in charge of the club after signing from Empoli in the summer of 2015.
Source: Serie A, Soccerway Rules for classification: 1) Points; 2) Head-to-head points; 3) Head-to-head goal difference; 4) Goal difference; 5) Goals scored; 6) Draw.[14] (C) Champions Notes:
^ abInternazionale finished ahead of Lazio on head-to-head points: Internazionale 0–0 Lazio, Lazio 2–3 Internazionale.
^Since the winners of the 2017–18 Coppa Italia, Juventus, qualified for European competition based on league position, the spot awarded to the cup winners (Europa League group stage) was passed to the sixth-placed team and the spot awarded to the sixth-placed team (Europa League second qualifying round) was passed to the seventh-placed team.