The court ruled that Kailajärvi had operated in a systematic manner to intentionally defraud thousands of people and to cause them losses. The state was also empowered to confiscate around six million euros in gains Kailajärvi received from his illegal activities. It ordered that his five-year sentence begin immediately.
Kailajärvi's lawyer said he would turn himself in on Friday morning, but police said soon afterwards that he had been taken into custody.
He has not paid whether he plans to appeal to the Supreme Court.
His female accomplice and former partner received a 15-month suspended sentence for aiding and abetting aggravated fraud and for violations of laws governing financial collections. The lower court had given her a one-year prison sentence.
According to the court, investors put 93 million euros into Kailajärvi's scheme between 2006 and 2008.