The 26-year-old follows in the footsteps of compatriot Betsy Hassett who joined the FA Women’s Super League debutants in January.
Kete is a City fan and has experience of playing in England after a brief spell with Lincoln Ladies in 2011.
The striker, who has also played in Canada, Finland and Australia, revealed she is impressed with City’s vision for the future and is keen to hit the ground running.
"It feels great to be here,” Kete said. "Manchester City has always been a well-recognised football club worldwide. A lot of my favourite players have passed through the club and some are still there.
"As a player, you want to be in the most professional, well-run environment in order to be the best you can be and from what I've heard, the club is striving to provide the women’s team with exactly that so that's one of the main attractions for me.
"I hope to come in and connect with the team as quickly as possible and contribute as much as I can to winning games. I want to make an impact and play some good, enjoyable football.”
City manager Nick Cushing added: "We are delighted to add Emma to our squad. Her previous international experience and past playing history only adds to the mindset and mentality to our team.
"Her ability adds to our creativity and her enthusiasm makes her a positive addition.
“We look forward to her joining up with the team as soon as possible."