A number of Premier League clubs have been keeping tabs on the 23-year-old wide-man in recent months.
Now Cardiff are ready to push ahead with a deal for Montero, who is currently playing with Mexican outfit Morelia.
Montero is now in the process of obtaining a visa which will allow him to travel to Britain and undergo a medical, ahead of the proposed deal.
There are not expected to be any issues over obtaining a work permit as he has nearly 30 caps for Ecuador, who are ranked 17th in the world, just behind England.
It will be the second time in his career that Montero has played in Europe as he spent three seasons in Spain with Villarreal, Levante and Real Betis before heading to Mexico in 2012.