The 29-year old Brazilian will join the Hammers for the remainder of the season with the view to a permanent shift to Upton Park.
"I am really happy to be here at West Ham," he told the club’s official website.
"Everyone has been very kind to me since I have been at the club this week. I think I can do my best here and I am coming to England to prove to everyone that I am one of the best strikers in Brazil and to get better and better.
"I am strong, I am a fighter and I can score with both feet. I run a lot on the pitch and I can play as either as first or second striker."
Wellington Paulista netted 10 goals for Cruzeiro last season as they finished ninth on Brazila’s Campeonato Serie A table.