Messi and his father, Jorge Messi, were convicted of defrauding Spain of €4.1m (£3.5m) between 2007 and 2009. They are set to appeal.
They also face huge fines after the court found they had used a web of shell companies to evade taxes from the player’s image rights. However, in Spain it is customary that those sentenced to under two years for non-violent crimes do not serve time in jail.
Now, Barcelona have rallied behind the Argentinian forward by launching the #WeAreAllLeoMessi campaign, encouraging fans to let Messi know he is not alone.
Barcelona's president Josep Maria Bartomeu took to social media himself to express his support on Friday.
However, critics have lambasted the decision to defend him.
Messi joined the club's academy in 2000, aged 13, and his family joined him in Spain soon after.
He made his competitive debut in 2004, at 17, and has now scored 453 goals in 531 appearances, winning five Ballon d'Or trophies for the world's best player along the way.
With Barcelona, he has won eight league titles and four Champions League winner's medals.
With additional reporting from PA Sport and Reuters