Rafa Zouhier, a Moroccan national, will be released March 16 on order of the Spanish National Court after being sentenced to 10 years in prison, TheLocal.es reported Thursday.
The former police informant could be deported upon his release. He has always maintained his innocence.
Zouhier was convicted in 2007 of having a role in the sale of explosives to Jamal Ahmidan, who headed a terror cell that killed 191 people and injured more than 1,800 in bombings of Madrid commuter trains in March 2004.
Some 28 people were arrested in connection with the bombing, ThinkSpain reported. Seven were found not guilty, including alleged terrorist Rabei Osman El-Sayed. Some 21 others were convicted.
Two members of the cell were given sentences totaling in excess of 42,000 years on 191 counts of homicide and 1,856 counts of attempted homicide.
Zouhier was given a lighter sentence because he was found innocent of a "necessary cooperation" charge. The court found the bombing could have proceeded without his involvement.
A miner who sold the explosives was sentenced to 34,715 years.