The 33-year-old will transfer from Welsh club Swansea City which dropped out of the Premier League after last season.
“West Ham is a great club, so I am really glad that I am able to join it at such an exciting time,” Fabiański said.
Fabiański, who is in Russia during the FIFA World Cup, has played on Poland’s national squad 45 times.
Fabiański who previously played for Londons Arsenal, was named Swansea City’s player of the season earlier this year.
He is set to debut in the West Ham jersey on August 11 when his new team takes on Liverpool. (vb)
Source: PAP