The 22-year-old forward has agreed terms with Rovers and will sign on a season-long loan deal from Audax Italiano, subject to a work-permit being attained.
Villanueva is the Chilean Player of the Year and has 12 caps to his name, and Rovers are confident that he will gain the permit needed to play in England.
New Rovers boss Paul Ince has hopes the deal can be confirmed within the next few days and he could become his first signing since taking charge at Ewood Park.
Villanueva has admitted to the Chilean media that he is waiting to seal his move to England.
"Hopefully something good will come, something that suits me and the club," he said.
"But I prefer not to talk about it too much until it is concrete."