The 22-year-old was another in a long line of skilful Argentinians who were likened to Lionel Messi when he broke through at River Plate as a 17-year-old.
The Hammers have been linked with a move for the tricky ace, who has a very similar style to Manchester United's Angel Di Maria, for over a month.
Somewhat bizarrely Lanzini, who holds an Italian passport, played in the footballing backwater that is the UAE Arabian Gulf League for Al Jazira last season.
And he will have to be ready for a huge jump in quality after the move was officially confirmed by his parent club on social networking website Twitter on Tuesday night.
West Ham are yet to confirm the signing their end but it is a deal aimed at unearthing a potential star with the club said to have the option to make it a permanent move should he impress in east London.
Lanzini is an Argentina Under 20 international who has a famously exciting obligatory YouTube clip of his silky skills, although his finishing leaves a lot to be desired.
Come in number seven
Co-owners David Sullivan and David Gold have been true to their word by investing significant funds to strengthen new boss Slaven Bilic's squad.
So far the East Londoners have brought in goalkeeper Darren Randolph on a free transfer, midfielders Pedro Obiang and Dimitri Payet for a combined total of around £15 million, defender Angelo Ogbonna for around £8 million and Carl Jenkinson in on loan again from Arsenal for a fee believed to be £2 million.
The Irons had already signed left back Stephen Hendrie from Scottish side Hamilton back in January and he officially became a West Ham player on July 1st.
But there has been the promise of more to come with Sullivan's son Jack confirming on Twitter ahead of Jenkinson's capture that the club will be trying to sign 'another three or four players'.
Lanzini is the seventh signing with the club now likely to turn their attentions to securing a striker.
South American gamble is low risk
The Hammers have always dipped their toe in the South American market under Sullivan and Gold.
From relative successes in Mexican Guillermo Franco and Brazilian Ilan to players who failed to win a place in the side like Brazilians Wellington Paulista and more recently Nene last season.
But the Upton Park faithful will be hoping Lanzini is more Tevez than Wellington and will be safe in the knowledge that if he can't cut it in the English top flight he will return to Al Jazira at the end of the season.
If it goes well they can seal the deal and everyone is a winner.