On 12 August 2017, Ziyech scored the opening goal in a 1–2 defeat to Heracles Almelo. On 20 August, Ziyech scored in a 3–1 win over Groningen. On 9 September, Ziyech missed a penalty but eventually scored just five minutes later in a 3–0 win over Zwolle. On 18 November, Ziyech provided an assist in an 8–0 win over NAC Breda. On 26 November, he provided an assist in a 5–1 win over Roda. On 14 December, Ziyech scored in a 3–1 win over Excelsior. On 20 December, Ziyech missed a penalty against his former club Twente, in the round of sixteen of the KNVB Cup, with Ajax suffering elimination after losing the penalty shootout. On 4 February 2018, Ziyech scored an injury-time goal in a 3–1 win over NAC Breda. Three days later, on 7 February, he scored in a 4–2 away win over Roda. On 18 March, Ziyech scored twice in a 5–2 away win over Sparta Rotterdam. On 19 April, Ziyech scored in a 4–1 win over Venlo.
On 1 September 2017, Ziyech scored in a 6–0 win over Mali, in a qualifying match for the 2018 FIFA World Cup. He was selected for the final 23-man squad for the 2018 FIFA World Cup.