The 28-year-old joined West Ham from Spanish club Real Betis in the summer of 2013 and has established himself as one of the best players in the team.
Adrian is one of the first names on the Hammers’ teamsheet and is the undisputed first-choice goalkeeper for the London outfit.
The former Betis star kept six clean sheets in 20 Premier League appearances in the 2013-14 season.
During the 2014-15 campaign, Adrian kept nine clean sheets in 38 league matches, while so far this term he has kept one clean sheet in four Premier League appearances.
After signing the new contract, Adrian took to Twitter to express his delight, with West Ham fans responding to his message on the social networking site.
@AdriSanMiguel not half as delighted as we are. Long may your reign last— david wilkinson (@wilko447) October 2, 2015