Pope Benedict XVI said in a decree that a French nun's recovery from Parkinson's disease was miraculous, the last step needed for beatification. A second miracle is needed for the Polish-born John Paul to be made a saint.
The May 1 beatification, which Benedict himself will celebrate, is expected to draw hundreds of thousands of pilgrims to Rome - a major morale boost for a church reeling from a wave of violence against Christians and fallout from the clerical sex abuse scandal.
Once he is beatified, John Paul will be given the title "blessed" and can be publicly venerated. Many people, especially in Poland, already venerate him privately, but the ceremony will make it official.
"This is a huge and important cause of joy," Warsaw Archbishop Kazimierz Nycz told reporters at his residence in the Polish capital.
Cardinal Stanislaw Dziwisz, John Paul's longtime secretary and friend, expressed "huge thanks" to Benedict for the decree. "We are happy today," he said.
Benedict put John Paul on the fast track to possible sainthood just weeks after he died in 2005, responding to the chants of "Santo Subito!" or "Sainthood immediately!" that erupted during his funeral.
Benedict waived the typical five-year waiting period before the process could begin, but he insisted that the investigation into John Paul's life be thorough so as to not leave any doubts about his virtues.
The last remaining hurdle concerned the approval by Vatican-appointed panels of doctors and theologians, cardinals and bishops that the cure of French nun, Sister Marie Simon-Pierre, was a miracle due to the intercession of John Paul.
The nun has said she felt reborn when she woke up two months after John Paul died, cured of the disease that had made walking, writing and driving a car nearly impossible. She and her fellow sisters of the Congregation of Little Sisters of Catholic Maternity Wards had prayed to John Paul, who also suffered from Parkinson's.
Last year, there were some questions about whether the nun's original diagnosis was correct. But in a statement Friday, the Congregation for the Causes of Saints said Vatican-appointed doctors had "scrupulously" studied the case and determined that her cure had no scientific explanation.
Born in Wadowice, Poland, in 1920, Karol Wojtyla was the youngest pope in 125 years and the first non-Italian in 455 years when he was elected pope in 1978.
He brought a new vitality to the Vatican, and quickly became the most accessible modern pope, sitting down for meals with factory workers, skiing and wading into crowds to embrace the faithful.
He was the most traveled pope ever, visiting more than 120 nations during the third-longest papacy and covering distance equal to nearly 1 1/2 trips to the moon.
His Polish roots nourished a doctrinal conservatism - opposition to contraception, euthanasia, abortion and women priests - that rankled liberal Catholics in the United States and Western Europe.
But his common touch also made him a crowd-pleasing superstar whose 26-year papacy carried the Roman Catholic Church into Christianity's third millennium and emboldened eastern Europeans to bring down the communist system.
He survived an assassination attempt in St. Peter's Square in 1981 - and then forgave the Turk who had shot him.
He died in his Vatican apartment on April 2, 2005 after suffering for years from the effects of Parkinson's disease. He was 84.
While adored by Catholics, John Paul did not escape scrutiny about the clerical abuse scandal which came to light in the final years of his papacy. Many of the thousands of sexual abuse cases that emerged in Europe and beyond last year concerned crimes or cover-ups that occurred under his watch.
Vatican officials have said there was nothing in John Paul's record that called into question his path to beatification.
Carl Anderson, head of the Knights of Columbus, one of the world's largest Catholic fraternal service organizations, noted that John Paul's beatification process is not a "score card on his administration of the Holy See."
Rather, he said, it's a statement about his personal sanctity since beatification is way of holding up Catholics as models for the faithful.
"Pope John Paul's life is precisely such a model because it was lived beautifully and with love, respect and forgiveness for all," Anderson told the AP in an e-mail. "We saw this in the way he reached out to the poor, the neglected, those of other faiths, even the man who shot him. He did all of this despite being so personally affected by events of the bloodiest century in history."
Associated Press reporter Vanessa Gera in Warsaw contributed to this report.