How can I get permanent residency in Portugal as a seasonal work visa holder?

You will need to obtain a temporary stay visa. This visa needs to be obtained at the Portuguese Consulate near your area of residence. The temporary stay visa is intended to allow entry and stay in Portugal for a period of less than one year for seasonal work for more than 90 days. The temporary stay visa is granted for the duration of the stay and is valid for multiple entries in Portugal.

In order to apply for permanent residency in Portugal, you need to hold a temporary residence permit for at least 5 years. During the five years of residency in Portugal, you cannot be convicted in a penalty or penalties that, isolated or cumulatively, overpass a year of prison even if the respective execution was suspended. You should have financial means of subsistence. You should have a physical residence in Portugal. You should have a knowledge on basic Portuguese (an A2 level certificate is required). Once these requirements are fulfilled, one can apply for permanent residency in Portugal. The application for a permanent residence permit is submitted at the Portuguese Foreigner and Borders Services (SEF) of the area of residence of the applicant, by himself or his legal representative and can be extended to minors depending on the applicant. As you will be entering Portugal as a seasonal work visa holder, that alone won’t enable you to apply for a permanent residence, as you won’t fulfill the above-mentioned criteria. As such, once in Portugal, you’ll have to apply for a temporary resident permit and maintain it for a least five years. Once that time has passed, and should the other criteria be fulfilled, you will be able to apply for a permanent resident permit.