Norwegian will reopen 76 routes and introduce 12 more aircraft from 1 July, the company said in a statement.
The re-opening routes include flights within Norway as well as to other parts of Europe. Flights will be launched to Spain, Greece and some European cities, for example.
From Helsinki-Vantaa Airport, Norwegian will start flying six times a week to Stockholm and three times a week to Oslo.
Norwegian justifies the opening of routes by increased demand and similar actions by competitors.
Due to the reopening of the routes, approximately 200 pilots and 400 cabin crew members may be called back to work.
Due to the new scheduled flights, Norwegian will redeploy 12 aircraft. Since then, the company has 20 aircraft in operation.
There is no catering on flights to minimise contact between passengers and cabin crew.