West Ham have signed Maz Pacheco following the left-back's departure from fellow Women's Super League club Reading.
It was announced last month that the 21-year-old would be leaving Reading at the end of her contract.
"She is a great attacking full-back," said manager Matt Beard, who gave Pacheco her senior debut at Liverpool in 2015.
"I'm looking forward to continuing her development as a player here.
" He added: "We've got ourselves a young, English, elite player.
The ambition for her now is to get into this West Ham team, play regularly, and hopefully we can help her fulfil her international ambitions too.
" The Hammers signed Australia international goalkeeper Mackenzie Arnold on Thursday.