The pair are were both found guilty of three counts of tax fraud, a statement from the court said on Wednesday. The Barcelona forward, 29, was fined about 2 million euros while his father received a fine of about 1.5 million euros.
Under Spanish law, any sentence under two years can be served under probation meaning the superstar and his father are unlikely to go to jail.
The pair were found to have used a number of fake companies in Belize and Uruguay to avoid paying taxes on just over 4 million euros worth of income earned through the sale of Messi's image rights between 2007 and 2009.
"All I knew was that we signed agreements with certain sponsors for 'X' amount of money and that I had to do advertisements, photos and those things but about the money and where it went I knew nothing."
The court said said this was not enough for him to avoid charges.
Messi and his father had already paid 5 million euros to the tax authorities as a "corrective" measure after formal investigations were opened.
Messi's testimony came before he played for his country in the Copa America, where they lost to Chile in the final, with Messi missing a penalty in the shootout. He retired from the international stage shortly after.