On 21 December 2008, when he was 16 years, he made his first team debut, playing ten minutes in a Serie A away match against Chievo; he is currently the eighth youngest player in the history of Serie A to have made his debut in the Italian top division. It was his only appearance of the season despite making the bench many times.

In June 2010 he was loaned out to Padova for the 2010–11 Serie B season. In his loan period at Padova, he quickly emerged as a key element for the team, leading the Venetian club to the promotion playoff finals where they then lost to Novara. He was awarded Serie B Player of the Year in 2011.

On 25 June 2011, El Shaarawy signed for Serie A giants Milan for €20 million transfer fee (€10M plus Alexander Merkel). On 18 September 2011, El Shaarawy made his debut with Milan at the Stadio San Paolo in a 3–1 loss to Napoli in Serie A. Three days later, after coming on as a substitute for the injured Alexandre Pato, he scored his first goal for the club, earning his team a 1–1 draw at home against Udinese.

He made his debut with the Italy U-21 team on 15 November 2011, in a qualifying match against Hungary.

In his first six months at Milan, he made a total of seven appearances leading to reports in the media that he may be loaned out for more playing time to help his progression. However a decision was made between vice-president Adriano Galliani, coach Massimiliano Allegri and himself to stay at the club for the near future. It was then that his performances for Milan began to improve and have led him to becoming one of the most highly rated youngsters in Italy. On 8 February 2012, El Shaarawy scored in a 1–2 loss against Juventus in the first leg of the 2011–12 Coppa Italia semi-final. Three days later, he scored an immensely vital winner against Udinese.

On 25 July 2012, El Shaarawy signed a new five-year contract with Milan. On 3 October 2012, he scored his first goal in UEFA Champions League against Zenit, thus becoming at the age of 19 years and 342 days, A.C. Milan’s youngest ever goalscorer in the competition. He scored two goals in a derby against Napoli to save Milan from losing an important game. El Shaarawy continued his fine form by scoring two more goals in a match against Catania, which ended 1–3 in favour of Milan. He then added a 76-minute goal in the thrashing 4–2 win over Torino FC and another in a 4–1 win over Pescara Calcio which contributed in Milan fourth consecutive win and up rising of the season. He finished the first half of the season as Serie A top scorer with 14 goals and also as A.C. Milan’s top scorer in all competitions with 16 goals.

In 2012 El Shaarawy was named one of the top players born after 1991 by Don Balón, and he was listed 52nd in The Guardian’s list of the best footballers in the world.

On 15 August 2012, El Shaarawy made his senior debut for Italy, in a 2–1 defeat in a friendly against England. El Shaarawy scored his first goal for Italy on his third appearance, on 14 November 2012 in a 2–1 friendly win against France.

In 2012, El Shaarawy signed a sponsorship deal with American sportswear and equipment supplier, Nike. He appeared in an advert for the new Nike Green Speed II alongside Mario Götze, Eden Hazard, Raheem Sterling, Christian Eriksen and Theo Walcott in November 2012.

On 28 February 2013, El Shaarawy ended speculation regarding his future by extending his contract for a further season, running until June 2018. In the second half of the 2012–13 season, El Shaarawy struggling to find his best form, but Milan CEO Adriano Galliani defended the player by stating that his goals kept Milan alive for the top three in the league.

After weeks of speculation surrounding his future, Milan officially announced on 2 July 2013 that El Shaarawy would not leave the club in the summer transfer window. On 20 August 2013, El Shaarawy scored his first goal in competitive club games since February 2013 against PSV in the Champions League playoff first leg. The first half of the season was led by injuries as he made only seven appearances in all competitions for Milan. On 28 December, after a surgery on his right foot failed to heal effectively, El Shaarawy was ruled out for a further ten weeks. He made his return on 11 May 2014 in the 2–1 Serie A loss against Atalanta.

In Milan’s first league match of the 2014–15 season against Lazio, El Shaarawy assisted Keisuke Honda in the seventh minute. On 8 November 2014, he scored his first Serie A goal in 622 days, and fell to the floor in tears. After his long absence through another injury, El Shaarawy scored a double in Milan’s 3–0 home victory over Torino, on 24 May 2015. He made just 28 appearances in all competitions during these two campaigns.

El Shaarawy was not included in Italy’s 2014 FIFA World Cup squad, after missing most of the 2013–14 season through injury.

On 13 July 2015, El Shaarawy joined Monaco on a season-long loan with an option to buy. He made his debut on the 28th, replacing Anthony Martial for the final seven minutes of a 3–1 away win over BSC Young Boys in the Champions League third qualifying round. In the second leg at the Stade Louis II, his first start, he scored his first Monaco goal in a 4–0 win. Before the start of the January transfer window, El Shaarawy was frozen out of the squad, as he had already played 24 games in all official competitions, 1 game short from activating the conditional obligation to buy him outright.

On 10 October 2015, El Shaarawy ended a three-year goal drought, scoring the winning goal in Italy’s 3–1 away win over Azerbaijan in a European qualifying match; this was his first international goal since November 2012, and the win guaranteed Italy a place at Euro 2016. On 31 May 2016, he was named to Antonio Conte’s 23-man Italy squad for the upcoming tournament. He made his only appearance of the tournament on 22 June, coming off the bench in Italy’s final group match, which ended in a 1–0 defeat to Ireland.

On 26 January 2016, El Shaarawy joined Roma on a loan deal until 30 June 2016, for a fee of €1.4 million. The agreement included an option to make the deal permanent, for a fee of €13 million, before the beginning of the 2016–17 season. Four days later, on his Roma debut, he scored a half scorpion flicked back heel goal in the 48th minute of a 3–1 home win over Frosinone; before scoring in the 94th minute three days later in the following match against Sassuolo to seal a 2–0 away win.

On 21 June 2016, Roma opted to buy out El Shaarawy’s loan from Milan for the €13 million, keeping him at the club until 2020. On 20 May 2017 he scored twice against Chievo to help Roma to a 5–3 victory as he continued a three-game scoring streak.

On 8 July 2019, El Shaarawy joined Chinese Super League club Shanghai Greenland Shenhua for €16m. He would make his debut for the club on 2 August 2019 in a league game against Wuhan Zall F.C. that ended in a 2–2 draw. This was followed by his first goal for the club on 15 August 2019 against Tianjin Tianhai F.C. in a 2–2 draw in a league game. At the end of his debut season with the club he would win the 2019 Chinese FA Cup by defeating Shandong Luneng Taishan F.C. in the final.

On 15 October 2019, El Shaarawy returned to the national team for the first time since the 2018 FIFA World Cup playoff defeat to Sweden in November 2017, also scoring in a 5–0 away win over Liechtenstein in UEFA Euro 2020 qualifying.