Amalfitano's inclusion - as announced on the Hammers' official website - is something of a surprise given that Slaven Bilic banished the former West Bromich Albion star from the club's first team for a 'breach of rules' last month.
He has not played any part in the West Ham first team since the club's ill-fated Europa League qualifying campaign.
Speaking in his column in the Evening Standard last month, Bilic explained his decision to order Amalfitano to train with the club's under 21s, saying: “I would just say that my first and foremost job is to protect the whole team - myself, the staff and players.
“If I see anything or anyone threatening to harm the atmosphere and transgress those rules, then it has to be stopped."
As a result, the 30-year-old was expected to leave the Hammers before the transfer window slammed shut on Tuesday and was linked with a return to his homeland with Saint Etienne, as reported by the Mirror.
But while fellow wide midfielder Matt Jarvis was loaned out to Norwich City, Amalfitano remained in East London despite the Hammers signing no fewer than four players on deadline day, two of whom were wingers Victor Moses and Michail Antonio.
Can Frenchman resurrect his West Ham career?
It remains to be seen whether the ex-Marseille man can resurrect his West Ham career now. He proved a shrewd signing by Sam Allardyce last season, scoring three important goals in 24 appearances.
He lost his way towards the end of the season, though, getting himself sent off within minutes of coming on as a second half substitute in West Ham's miserable 4-0 defeat to his old club West Brom in the FA Cup.
Other than Amalfitano's inclusion, there were no real surprises in Bilic's first official 25-man squad which will be available for selection for Premier League matches between now and the opening of the January 2016 transfer window.
In addition to the 25 senior players, the club has also named eight Under-21 players born on or after 1 January 1994, who are also available for selection – Josh Cullen, Stephen Hendrie, Sam Howes, Kyle Knoyle, Elliot Lee, Lewis Page, Martin Samuelsen and West Ham's youngest ever player Reece Oxford.
West Ham comfortably meet Premier League rules regarding homegrown players, with the 25-man squad alone including 11 such players.
West Ham's 25-man squad list in full:
Adrian, Morgan Amalfitano, Michail Antonio, Andy Carroll, James Collins, Aaron Cresswell, Doneil Henry, Nikica Jelavic, Carl Jenkinson, Cheikhou Kouyate, Manuel Lanzini, Victor Moses, Mark Noble, Joey O’Brien, Pedro Obiang, Angelo Ogbonna, Dimitri Payet, Darren Randolph, Winston Reid, Diafra Sakho, Alex Song, Raphael Spiegel, James Tomkins, Enner Valencia, Mauro Zarate.