[7] The following week, however, Diamanti signed a five-year deal with Premier League club West Ham United for an undisclosed fee.

[9] He scored his first West Ham goal from the penalty spot, albeit controversially as he fell over on run up and kicked the ball with both feet, on his home debut against Liverpool on 19 September 2009.

Diamanti's sixth goal came in a 2–1 loss against Catania which confirmed Brescia's relegation to Serie B, just one season after promotion to the top-flight.

[23] Diamanti scored the winning goal of a 3–1 away victory over Lazio on 11 March 2012 with a 30-yard strike over out-of-position goalkeeper Federico Marchetti.

[26] Diamanti put the finishing touches on a comfortable 3–0 defeat of Palermo on 18 November, netting from the penalty spot in the 48th minute.

[27] On 2 December, Diamanti netted from a free-kick as Bologna earned a hard-fought 2–1 victory over Atalanta, courtesy of a second-half goal from teammate Manolo Gabbiadini.

[28] Two weeks later, on 16 December, Diamanti proved instrumental in Bologna's surprise 3–2 defeat of high-flying Napoli, providing the free-kick from which Daniele Portanova headed in a minute from time to secure the victory.

[31] He made his debut appearance for Guangzhou in a 4–2 win over Melbourne Victory on 26 February 2014 in the first group match of the 2014 Asian Champions League.

[34] On 17 August 2015, Diamanti signed for English Premier League club Watford, on loan from Guangzhou Evergrande, subject to international clearance.

[44] He missed the second half of the 2021/22 season due to a knee injury, watching from the stands as his side won the A-League championship in their first Grand Final appearance.

[4] Diamanti made his debut with the Italy national team on 17 November 2010, for manager Cesare Prandelli, in a friendly match against Romania.

[53][54] Nicknamed "Alino",[55] Diamanti was a dynamic, creative and technically gifted left-footed playmaker, who usually played as an attacking midfielder; he had also been deployed as a winger or as a supporting striker on occasion, due to his ability to both create chances for teammates, and score goals with his accurate striking ability from outside the area, despite his lack of pace.

[56][57][58][59][60] In addition to his flair and playing ability, he is also known for his charismatic personality, tenacity, and leadership on the pitch;[61] moreover, he is a player who wins a lot of fouls for his team.