"They have called him as witness," a spokesman for the National Court that deals with major corruption cases told AFP, adding no date had been set yet for the hearing.
Rajoy will take the stand as part of the so-called Gurtel trial, which centres on a vast network that allegedly saw companies shower former lawmakers and civil servants from his ruling Popular Party (PP) with bribes in exchange for contracts.
Altogether, 37 defendants face justice including two former party treasurers and businessman Francisco Correa, the alleged head of the network.
The PP itself is on the stand via a legal representative, though unlike most other defendants who face criminal charges, the party is accused only of having benefitted from funds obtained illegally, making it liable to civil penalties.
Rajoy's former health minister Ana Mato, who was forced to resign in November 2014 over the scandal, is also on the stand though like the PP she is suspected only of having benefitted from illegal funds.
Corruption is a major issue in Spain, with the PP, rival Socialists and regional politicians hit by scandals.
Such is public anger over the issue that many voters have flocked to two relatively new parties -- the far-left Podemos and the centre-right Ciudadanos.
As a result, although the PP still won general elections last year, it failed to get the absolute majority it won in 2011, and Rajoy now heads a minority government.