Sam Allardyce's side ended up with a 13th-placed finish in the Premier League last season having spent much of the campaign near the bottom of the table.
He told the club's official website: "We already have a good backbone of defensive qualities in our squad.
"I think that was proved with the 14 clean sheets we achieved last season and to add more in the attacking sense on top of that, can only be a good thing for the whole team.
"The gaffer and the owners have been working hard to secure new additions to our squad, including in attack, and these will add to what we have here already and help us to push on next season to finish higher up in the Barclays Premier League and we look forward to that."
West Ham kick off their Premier League campaign by hosting Tottenham Hotspur on August 16.