The news came at a sensitive time in Spanish politics, where bickering between parties is edging the country towards its third election in a year, reports Reuters.
He stepped down as minister in April after reports surfaced of his alleged links to an offshore company on the British island of Jersey, saying he was resigning to limit any damage to the caretaker government. Soria has denied any wrongdoing.
The conservative People's Party (PP) has governed in an acting capacity since losing its majority in an inconclusive election in December following a string of corruption scandals.
The PP again won the most votes in a second ballot in June, but still fell short of a majority in another hung parliament.
Parties have yet to find a way out of the impasse, and PP leader Mariano Rajoy has struggled to get enough rivals to back him for a second term in office.
Soria's nomination to the executive director position at the World Bank prompted the PP's political rivals to demand explanations in parliament from acting Economy Minister Luis de Guindos.
Rajoy shrugged off the appointment on Monday, saying Soria was no longer a political figure, but even some regional PP leaders showed their discomfort in recent days and questioned his nomination.
Close to 290,000 people had by Tuesday signed an online petition asking the World Bank to veto Soria's appointment