Ordained a priest in 1789, he had an uneventful early career, though his interest in the economic advancement of his parishioners in Dolores, through the introduction of newer methods of agriculture, made him suspect by the Spanish authorities. In 1808 Spain was invaded by French troops, and Napoleon forced the abdication of King Ferdinand VII in favour of the French emperor's brother Joseph Bonaparte. Though Spanish officials in Mexico were loath to oppose the new king, many Mexicans formed secret societies—some supporting Ferdinand, others independence from Spain. Father Hidalgo belonged to such a group in San Miguel, near Dolores. When the plot was betrayed to the Spanish, several members were arrested. Warned to flee, Hidalgo decided instead to act promptly. On September 16, 1810, he rang the church bell in Dolores (Grito de Dolores) to call his parishioners to an announcement of revolution against the Spanish. What he began in San Miguel as a movement for independence became a social and economic war of the masses against the upper classes. Thousands of Indians and mestizos flocked to Hidalgo's banner of Our Lady of Guadalupe, capturing Guanajuato and other major cities west of Mexico City. Soon Hidalgo was at the gates of the capital, but he hesitated and the opportunity was lost. His followers melted away. The responsible elements in Mexico were frightened by the prospect of social upheaval. After his defeat at Calderón on January 17, 1811, Hidalgo fled north, hoping to escape into the United States. He was caught, degraded from the priesthood, and shot as a rebel.

Though he accomplished little, Father Hidalgo's name became the symbol of the independence movement for most Mexicans, and September 16, the anniversary of the Grito de Dolores, is celebrated as Mexico's Independence Day.