The Gunners are set to pay Swedish club Hammarby around £140,000 for the midfielder ahead of the Women’s Super League campaign starting next month.
Cooney-Cross was in London today to undergo a medical with Arsenal and sign before tonight’s transfer deadline.
The 21-year-old shone for Australia at the Women’s World Cup this summer and had been attracting interest from Chelsea and Manchester United.
The Gunners have moved fast to snap up Cooney-Cross now before she became a free agent in January, when her contract was due to expire.
Arsenal have embarked on an aggressive recruitment drive for their women’s side this summer, bringing in Manchester United striker Alessia Russo.
The club crashed out of the Champions League last week in the qualifying rounds, but they have continued to invest in the squad by sanctioning a deal for Cooney-Cross on deadline day.