In its judgement, the tribunal said Kerviel had been fired "without genuine or serious cause" and that the bank had full knowledge of his shady dealings long before he was fired in 2008.
A lawyer for Societe Generale, Arnaud Chaulet, said he would appeal the "scandalous" decision, recalling that Kerviel had been found guilty of gambling away €4.9 billion ($5.5 billion) of the bank's money.
Kerviel has long argued he had been made a scapegoat in the case.
The trader was sentenced to three years in prison in 2010, but was released in September 2014 after spending less than five months behind bars.
He was convicted of breach of trust, forgery and entering false data, but claimed his bosses turned a blind eye as long as the profits kept rolling in.