In 2019 Mastour returned to Italy, playing for Reggina and Carpi in the Serie C. After being clubless for one year, he signed for Renaissance Zemamra in the Moroccan Botola 2, contributing to their promotion back to the first tier.

[5] On 31 August 2015, Mastour was loaned to Spain's Málaga CF for two seasons, at the exclusive request of club owner Abdullah al-Thani;[6] as a minor, his transfer to another country had to be approved by FIFA, which was not completed until 5 November.

[7] He was first included in a matchday squad for the La Liga home fixture against fellow Andalusians Real Betis two days later,[8] making his competitive club debut in the eventual 0–1 loss by playing five minutes as a substitute for compatriot Adnane Tighadouini.

[11] He made his Eredivisie debut on 13 August, replacing fellow Moroccan Youness Mokhtar for the final 17 minutes of a 0–3 home loss to Sparta Rotterdam.

[13] On 4 September 2018, Greek Superleague club Lamia officially announced the signing of Mastour on a free transfer, on a contract worth €200,000 per year.

[24] He made his international debut on 18 August 2013, playing the first half of a 3–0 friendly victory over Qatar in Borgo Valsugana,[25] and scored a late equaliser in a 2–1 win over Croatia in Umag on 11 March the following year.

[27] On 12 June 2015, he made his international debut for Morocco in a 2017 Africa Cup of Nations qualification Group F match against Libya at the Stade Adrar in Agadir, replacing Nordin Amrabat for the final two minutes of the 1–0 victory.

[3] In 2015, Fabio Balaudo of UEFA.com added: "Excellent dribbling skills and sublime technique have made him almost impossible to mark for players in his age group.

With great control at speed, a good shot with both feet and the ability to change pace, he is expected to shine behind the forwards or as a winger.

[3][32] Several pundits, including Ivano Pasqualino, have also highlighted Mastour's ball-juggling skills and prowess at free-style football as some of his key strengths and characteristics as a player.

[40] Despite his talent, however, he has since struggled to establish himself at the professional level and consistently achieve first team football;[17][41][42][43] as such, various pundits have questioned whether he is capable of handling the pressure needed to fulfil his potential.