The English club has signed Castellanos on a four-and-a-half-year deal.
The Argentine striker has left Italian football for England, joining West Ham United on a long-term contract.
West Ham confirmed on Monday that the 27-year-old forward has signed for four and a half years, with an option to extend the deal by an additional year.
Castellanos joined Lazio in 2023. During his time in Serie A, he played 52 matches and scored 16 goals, including 10 goals last season alone.
West Ham stated that they will have Castellanos available for Tuesday’s match against Nottingham Forest.
Currently, West Ham are in the relegation zone of the Premier League. They have failed to win in their last nine league matches, and after 20 matches this season, they sit 18th in the table with 14 points.
