Javier 'Chicharito' Hernandez will wear No.17 with West Ham, the club announced Wednesday.
The Mexico international ditched his traditional No. 14 following his transfer back to the Premier League after spending two seasons with Bayer Leverkusen.
Chicharito was presented at West Ham last week, returning to England for the first time since leaving Manchester United in 2016. He had spent the 2015-16 season on loan at Real Madrid.
The forward will likely make his West Ham debut against the Red Devils when the teams meet in the first match of the Premier League season on August 13.
"It's going to be a very special weekend. Who would've thought my return to the English league would be playing at the place I called home with my old club?" Hernandez told Fox Sports .
"It'll be really nice. I'm very motivated, very hopefully to be there that weekend, also just because it'll be start of the season."
Chicharito became Mexico's all-time leading scorer in May, with 48 goals in 96 appearances.