The prosecutors' office in Madrid confirmed to ESPN FC that Mourinho appeared before a judge in a Madrid court to ratify the plea bargain agreement he had reached with the tax office.
The former Manchester United manager was accused of owing Spanish tax authorities almost €3.3 million (£2.9million).
Prosecutors said he had created offshore companies to manage his image rights and hide the earnings from tax officials.
The 45-year-old Norwegian football manager replaced Mourinho could soon be made permanent if he continues his unbeaten run since taking charge.
Legit.ng earlier reported that Jose Mourinho has been found guilty of evading tax during his time managing Spanish League giants Real Madrid.
Mourinho failed to declare revenue from image rights from 2011 and 2012 during his time at Real Madrid.
They argued that was created to obscure his financial gain from such deals - and he left it undeclared in his tax statements after he moved to Spain.
As well as the one-year prison sentence, Mourinho has been fined €1.9 million, 60 per cent of the amount defrauded, as well as €121,764 in interest.
Ronaldo received a two-year jail sentence immediately commuted to a fine of 365,000 euros and another penalty of 3.2 million euros, according to the sentence. He must also cover legal costs.