Colombia midfielder Carlos Sanchez joined from Fiorentina and a long-running deal to bring striker Lucas Perez from Arsenal was also completed, meaning that manager Manuel Pellegrini has added nine players to the squad ahead of his first season at the club.
Perez has joined West Ham from Arsenal on deadline-day.
Champions League hat-trick aside, Perez never got going for the Gunners after joining from Deportivo la Coruna for £17million, and will therefore undoubtedly retain "flop" statue forever more.
West Ham already boast Javier Hernandez and Andy Carroll up front, while Toni Martinez has impressed in pre-season and Marko Arnautovic can play up front.
"There are other clubs interested but joining West Ham would allow him to continue in London and in the Premier League and Lucas wants to continue in London".
Financial details of the deal were not disclosed, but local media said West Ham had paid about 4 million pounds for the Spaniard.More news: PS4 Pro is getting a 500 Million Limited Edition release
"I'm very happy to be here at such an historic Club", Perez told the club's official website.
"He has great technical quality, and can play as both the main striker or the second striker in a deeper role".
"I'm very happy to be here".
"In Spain there are also interest from some clubs, but they are not willing to assume the transfer".
This is in view of the fact that Andy Carroll is set to miss West Ham's season opener at Liverpool on Sunday due to injury.