The country’s Supreme Court opened an investigation in June into his involvement in a high-speed train contract in Saudi Arabia that was awarded to Spanish companies in 2011.
The investigation came after the Swiss newspaper La Tribune de Genève announced that it had received $ 100 million (£ 75 million) from the late Saudi King Abdullah.
The former Spanish monarch then reportedly transferred a large sum to a businesswoman, which investigators see as a possible attempt to hide the money from authorities.
Juan Carlos, 82, declined to comment on the allegations. His lawyer, Javier Sanchez-Junco, said that despite his decision to leave, the former king “would remain at the disposal of the prosecution”.
Allegations of corruption have eroded public confidence in the country’s monarchy.
Earlier today, Juan Carlos had informed his son, King Felipe, of his intention to leave.
“I inform you of my considered decision to move, during this period, out of Spain, ” he said in a letter posted on the Royal Family website.
Juan Carlos said he made this decision against the backdrop of “the public repercussions that certain past events in my private life have caused”.
He said he wanted to make sure he didn’t make his son’s role as monarch difficult.
King Felipe, 52, thanked Juan Carlos for his decision, stressing “the historical importance that his father’s reign represents” for democracy in Spain.
But Deputy Prime Minister Pablo Iglesias, who heads the far-left Podemos party in the ruling coalition, called the decision to leave the country “an act unworthy of a former head of state” and called declared that it compromised the monarchy.
In March, King Felipe gave up his own inheritance and stripped his father of his palace allowance after corruption allegations surfaced.
Spanish monarchs enjoy immunity during their reign but Juan Carlos abdicated in 2014, leaving himself potentially vulnerable to prosecution.
El Mundo newspaper reported that he had left Spain. We did not know where he was now.
Juan Carlos ascended to the throne in 1975 after the death of General Francisco Franco and was widely respected for his role in helping to guide Spain from dictatorship to democracy.
But his popularity sank in the following years due to a series of scandals, which led him to resign.
An expensive elephant-hunting trip he took to Botswana in 2012 sparked outrage at a time when Spain faced austerity, recession and soaring unemployment. He apologized later.
Her daughter, Princess Cristina, was charged with tax evasion in 2014 and became the first Spanish royal to stand trial. She was acquitted in 2017, but her husband Inaki Urdangarin was sentenced to almost six years in prison.