The big gold miner said a syndicate of underwriters have agreed to buy 8.4 million shares of Primero at a price of $5.25 per share.
Primero shares closed up seven cents at $5.49 on Tuesday.
Once the sale is completed, Goldcorp will continue to hold nearly 31.2 million shares in Primero, representing a 32 per cent stake in the company.
Primero, which owns the San Dimas gold-silver mine in Mexico, will not receive any money from the offering.
In addition to the San Dimas mine, Primero owns the Ventanas property in Mexico. Ventanas includes 28 mining concessions covering about 35 square kilometres and 17 old mines and workings.
Goldcorp is Canada's second-largest gold company.
The company has mines as well as exploration and development projects in Canada, the United States, Mexico and Guatemala and Argentina.