In fervent displays of devotion, huge crowds of men, women and children chanted "Viva!" (Long live!) and twirled white handkerchiefs at the Black Nazarene, with some hurling themselves at the supposedly miraculous statue for good luck.
"The Lord is my healer," Lina Javal, 58, declared after waiting in line for hours to kiss the life-sized ebony statue, showing an AFP reporter the healed incision from throat surgery she underwent last month.
The mammoth procession, estimated by the Philippine Red Cross at 5.5 million people, crawled at a near-snail's pace along Manila's old quarter as devotees risked life and limb for the privilege of pulling the fat rope that moved the float forward.
City officials and the Philippine Red Cross said a man died from heart attack and more than 600 others were treated for various injuries as the crowd wriggled past trash-strewn streets in light rain and overcast skies.
The procession is expected to last well into the night.
She carried the two-year-old boy, who is blind in his right eye, to the parade, shielding him from the rain with a blanket.
Many Filipinos believe the statue holds miraculous healing powers and make lifetime vows to join the annual parade, often wearing T-shirts emblazoned with an image of Christ crowned in thorns.
"The brand of religious devotion that we see in Filipino Catholicism is based on a very strong desire of the majority of our people for a more immediate and direct access to divine help or power," Manuel Victor Sapitula, a sociology professor at the University of the Philippines, told AFP.