Earps will officially link up with the Lionesses on July 1st, following the conclusion of her contract at PSG.
The 33-year-old, who won Euro 2022 with England, spent two seasons at PSG after leaving Manchester United in 2024.
London City, owned by American billionaire Michele Kang, enjoyed a successful debut in the WSL last season, finishing sixth in the table.
"I'm over the moon to join this club and I'm really looking forward to it. I feel the club aligns with what I stand for," said Earps, who won 53 England caps before retiring from international duty last year.
"The club's values represent what I want to represent and they are passionate about what I want to achieve and change the game in a positive way.
"The vision and ambition, including the new training facility, is incredible and I'm looking forward to seeing that develop. It shows what our owner, Michele (Kang), and everyone at the club want to do in terms of really going for it."
