The 26-year-old, who has 80 Sweden caps, has also played at Linkopings, Chicago Red Stars and Kristianstad.
Asllani joins the Blues before the new Women's Super League season, which gets under way on Wednesday, 23 March.
"This team has a lot of potential and ambition. They want to win titles and I want to help them to do so," she said.
Manchester City Women have signed Sweden international striker Kosovare Asllani on a two-year deal from Paris St-Germain.