Early career Born in
Nice, Alpes-Maritimes, On 23 December 2009, Amalfitano scored two goals as
Lorient twice came from a goal behind to defeat
Valenciennes 3–2. On 28 March 2010, Amalfitano provided an assist and scored a goal as
Lorient completed a 4–0 rout over
Saint-Étienne. On 5 May, Amalfitano had a hand in both goals as
Lorient drew 2–2 with
Monaco, scoring his side's first equalizer before setting up
Kevin Gameiro for a late equalizer that secured a point for the club. On 6 November 2010, Amalfitano provided assists for both of Gameiro's goals as Lorient defeat
Saint-Étienne by a score of 2–1. In three seasons with the club, Amalfitano played 121 matches and scored 15 goals in all competitions. .
Marseille In July 2011, Amalfitano joined
Marseille on a free transfer, signing a contract until 2015. He made his debut for the club in the
Trophée des Champions against
Lille in a 5–4 win on 27 July, coming on as a substitute and later hitting the woodwork with his first show for the club. His competitive debut for the club came on 6 August in the first round of the new
Ligue 1 season, he was substituted in the 66th minute for
Mathieu Valbuena as Marseille had to settle for a 2–2 draw at home to
Sochaux. He made his
Champions League debut in a 1–0 win against
Olympiacos on 13 September 2011. He scored his first goal for the club on 27 November 2011 in a 3–0 home victory against
Paris Saint-Germain, as well as providing the assist for
Jordan Ayew's goal that sealed the emphatic win. On 6 December 2011, in the final match of the group stage of the Champions League, Amalfitano provided assists for
Loïc Rémy and
André Ayew as a late Valbuena strike earned Marseille a 3–2 victory over
Borussia Dortmund and a place in the knockout phase. Amalfitano played the full 120 minutes on 14 April 2012 as Marseille defeated
Lyon 1–0, thanks to a late
Brandão strike, to win the
Coupe de la Ligue trophy. Amalfitano finished the season with 49 appearances for the club, but the up-and-down campaign which ended with the club missing out on the
Champions League resulted in Amalfitano asking for a transfer request.
West Bromwich Albion (loan) in December 2013. On 1 September 2013, it was confirmed that Amalfitano had signed for
West Bromwich Albion on a season-long loan deal with a view to a permanent transfer. He scored his first goal for West Brom against
Sunderland on 21 September 2013 in a 3–0 win. Four days later he played as a substitute in a
League Cup tie against
Arsenal; the game went to penalties and Amalfitano missed the decisive kick as Arsenal won. He scored his second league goal the following weekend, taking the ball from midfield and then knocking it through
Rio Ferdinand's legs, Amalfitano then nonchalantly dinked the ball over
David de Gea, helping West Brom to a 2–1 victory over
Manchester United at Old Trafford, their first win at Old Trafford since 1978. After a positive start to life at
The Hawthorns, his form declined up until the run-in in which he scored an audacious lob from 35 yards in the thrilling 3–3 draw against fellow relegations rivals
Cardiff City on 29 March 2014. He followed that strike up the following week with the solitary goal in West Brom's away win over
Norwich City. Upon finishing his loan at West Brom, he returned to Marseille in July 2014.
West Ham United On 1 September 2014, Amalfitano signed for
West Ham United on a one-year deal for an undisclosed fee. He made his West Ham debut two weeks later against
Hull City on 15 September, replacing
Diafra Sakho in the second half of the 2–2 draw. On 20 September 2014, Amalfitano made his home debut for the Hammers, coming on in the second half and scoring his first goal for West Ham, against
Liverpool, to complete a 3–1 victory and secure the club's first home win of the season. Amalfitano's second goal for the club came on 25 October at home to
Manchester City when he netted the opener in a 2–1 victory over the reigning champions. Amalfitano replaced
Kevin Nolan after 60 minutes of West Ham's FA Cup fifth-round game at West Brom; ten minutes later he was booked for a heavy challenge. He then put his hand in an opponent's face resulting in the referee issuing the red card in an eventual 4–0 defeat. In March 2015, Amalfitano signed a new, two-year contract with West Ham which would keep him at the club until the end of the 2016–17 season. In August 2015, Amalfitano was disciplined for a breach of club rules by new manager
Slaven Bilić. Amalfitano was banned from the first-team squad and ordered to train with the under-21 team. On 6 October 2015, Amalfitano left West Ham by mutual consent.
Lille On 7 January 2016, Amalfitano joined French side
Lille on a two-and-a-half-year deal upon his contract expiry from West Ham United in 2015.
Stade Rennais On the final day of the 2016–17 winter transfer window, Amalfitano agreed to the termination of his contract with Lille before rejoining his former coach,
Christian Gourcuff, at
Stade Rennais F.C. He signed a 2.5-year deal with the club. In August 2018, Amalfitano agreed the termination of his contract with Rennes. ==After retirement==