He made his debut for the B-team in March 2014, and scored in his first match for the senior team in August of that year, at the start of a season in which they won the treble.

His mother, Saida Mohamed Haddou, hails from the Spanish autonomous city of Melilla on the north coast of Africa; she is a former kitchen hand who now looks after Munir's three siblings.

[5] After starting at Galapagar and DAV Santa Ana, Munir scored 32 goals in 29 matches playing for CF Rayo Majadahonda's Cadete A team, on loan from Atlético Madrid, after impressing during a trial in 2010.

[18] On 17 December, starting due to Messi and Neymar's injuries in the semi-finals of the 2015 FIFA Club World Cup in Yokohama, Munir won a penalty kick when fouled by Guangzhou Evergrande Taobao's Huang Bowen, from which Luis Suárez finished his hat-trick to send Barcelona into the final, 3–0.

[20] On 13 January 2016, profiting from Suárez's suspension, Munir scored both goals in a cup win at city rivals Espanyol, putting Barcelona into the quarter-finals 6–1 on aggregate.

[25] Munir made his debut on 11 September, replacing Santi Mina after 63 minutes of a home game against Real Betis, and his rebounded header was scored by Ezequiel Garay in a 2–3 defeat.

[36] Munir scored a hat-trick on 7 November 2019 in a 5–2 Europa League group win at F91 Dudelange, which put his team through to the last 32 and bought his tally in the competition to five.

In doing so, Munir equalled a record held by Carlos Aranda, Roberto Soldado, and Miquel Soler of scoring for seven different La Liga clubs.

[5] On 29 August 2014, Munir was called up for the first time as one of 21 players for Albert Celades' Spain under-21 team to face Hungary and Austria in September.

[44] However, after an injury to Diego Costa, Vicente del Bosque called Munir up to the senior squad for the first time ahead of a UEFA Euro 2016 qualifier against Macedonia on 8 September.

[47] In June 2017, it was reported Munir and the Royal Moroccan Football Federation (FRMF) had contacted FIFA to change his allegiance to Morocco.

[48] On Munir and the FRMF's request, the Court of Arbitration for Sport began debating FIFA's rules on switching allegiances in April 2018.

[52] On 28 January 2021, FIFA published the eligibility requirements for national teams, and Munir received the green light to represent Morocco, as he played once for Spain before he turned 21.

[53] Munir made his debut for Morocco on 26 March 2021, playing the full 90 minutes as the team drew 0–0 away to neighbouring Mauritania to qualify for the 2021 Africa Cup of Nations.

[57] After his goalscoring debut, Barcelona manager Luis Enrique praised Munir as a player whose effort in training matches that on the pitch, but warned against getting carried away with his performance.