The controversial 29-year-old moves back to Upton Park for the second time after his 6-month spell during the relegation season of 2003.
Hammers boss Alan Pardew told the official site, “I am delighted to have a player of Lee's calibre on board.
”He is one of the most talented midfield players in the country but he has won nothing. I am convinced that is now going to change.”
Bowyer himself was delighted to be coming back to his roots.
Lee said, “I am desperate to do well for West Ham. I loved my time at Newcastle but this is my Club.
”I didn't play well last time. I had a bad ankle injury and kept playing on it which was to nobody's benefit. I see this as unfinished business - I want to show the Hammers fans what I can do.”
Despite Bowyer's obvious talent his on and off the field discipline problems have been well documented and Pardew had some words of warning for his new signing.
“All those incidents that Lee has been involved with down the years have taught him lessons and everyone deserves another chance. I will not tolerate any other incidents, he now needs to have a clean bill of health.
”We had a fantastic disciplinary record last season - one sending-off all year speaks for itself. Lee needs to understand they are the standards we have set and I expect him to abide by them.”