Manchester United triggered a one-year extension in Valencia's contract on 17 January 2017, keeping him at the club until 2018. On 19 March 2017, Valencia made his 200th league appearance for United and scored in injury time, after goalkeeper Víctor Valdés slipped, to complete a 3–1 victory over Middlesbrough. On 26 May 2017, two days after captaining United in the 2017 UEFA Europa League Final, his contract at the club was extended until June 2019, with an option to extend for a further year. On 17 September 2017, Valencia scored his first goal of the season in a 4–0 win against Everton with a 20-yard half-volley. Later on 14 October, Valencia captained the team in his 300th appearance as Manchester United drew 0–0 at Liverpool. After being ruled out for four weeks with a hamstring injury, Valencia returned to action as he scored the opening goal in a 3–0 home victory against Stoke City in January 2018.