Darmian made his first appearance of the 2017–18 season on 8 August 2017 against Real Madrid in the UEFA Super Cup, which United lost 1–2. His first Premier League appearance of the season was on 9 September, in a 2–2 draw against Stoke City. He didn't feature again in the league until 14 October in a 0–0 draw against Liverpool at Anfield. While not featuring in the league, Darmian did play in the UEFA Champions League in a 2–0 win over Benfica on 31 October and in a 1–0 defeat against Basel on 22 November. On 20 December, he played in United's 2–1 defeat to Bristol City in the EFL Cup fifth round. Darmian made his first league start since October on 18 April 2018, playing against Bournemouth in a 2–0 victory. Three days later, he came off the bench in the 80th minute to see out United's 2–1 victory over Tottenham Hotspur in the FA Cup semi-final at Wembley Stadium. Darmian started in United's last league game of the season on 13 May, overseeing a 1–0 win over Watford at Old Trafford. He was left on the bench for Manchester United's 1–0 defeat to Chelsea in the FA Cup Final on 19 May. After falling out of favour with José Mourinho, Darmian only managed eight league appearances the whole season, five of which were starts.