Trains from Thessaloniki to Florina are due to resume service on Sunday.
The line had been out of service since the start of 2011.
The Hellenic Railways Organization (OSE) said it has found a way to make the line, which used to carry an average of just 200 passengers a day, profitable.
OSE has struck a sponsorship deal with the Public Power Corporation worth 420,000 euros a year for the next three years to help cover the cost of operating the line.
Before being suspended, the service cost 2 million euros per year but only earned 800,000 euros per year in revenues.