Beneath the glow of traditional chandeliers and modern spotlights, which illuminated its intricately carved stonework, the cathedral emerged reborn, its grandeur restored after five years of reconstruction.
For Catholics, it marks the revival of the city's spiritual heart, a place where faith has been nurtured for centuries. For the world, it signals the rebirth of one of global heritage's most famous landmarks.
The event on Sunday was both solemn and historic. Archbishop Laurent Ulrich presided over the morning Mass, including the consecration of a new bronze altar.
The liturgy was attended by 2500 people, including French President Emmanuel Macron — enjoying a brief respite from France's political tumult and economic troubles — clergy, dignitaries and a few lucky members of the general public who stood in long lines to enter.
Emmanuel Macron and his wife Brigitte Macron were in the congregation. (AP PHOTO)
Nearly 170 bishops from France and around the world took part, along with one priest from each of the 113 parishes in the Paris diocese, accompanied by worshippers from these communities.
Notre Dame's journey from ruin to resurrection was defined by extraordinary craftsmanship, nearly $US1 billion ($A1.6 billion) in global donations and a collective, unyielding determination to rebuild.
After the Mass, priests, nuns, and other guests lingered in the cathedral, their awe evident.
Many took pictures and selfies in front of the altar, the baptistery, and vibrant rose windows, their joy mingling with reverence. Others knelt to pray at chapels dedicated to saints, savouring a spiritual intimacy many had not experienced since the fire.
The reopening of Notre Dame has sparked a moment of cultural and national unity. (AP PHOTO)
Later on Sunday, the cathedral opened its doors to members of the public who secured reservations last week for the first fully public Mass.
Sunday's Masses follow Saturday evening's ceremonies in which Ulrich symbolically reopened the cathedral's massive wooden doors by striking them three times with a crosier crafted from charred beams salvaged from the fire.
As the doors swung open, choirs filled the air with song and the cathedral's great organ resounded with majestic melodies.
Inside, the restoration reveals a cathedral transformed with now-gleaming limestone walls cleaned of centuries of grime. The restored stained-glass windows project dazzling patterns of colour across the nave.
"No one alive has seen the cathedral like this," said the Reverend Olivier Ribadeau Dumas, Notre Dame's rector. "It is more than restored — it is reborn."
The liturgy was attended by 2500 people who waited in the rain for the chance to worship. (AP PHOTO)
The reopening of Notre Dame is also a moment of cultural and national unity.
Macron, who vowed to restore the cathedral within five years after the fire, called the project "a jolt of hope" for France, a nation often divided by political crises.
The Sunday Masses underscore Notre Dame's dual role as a place of worship and a symbol of communal resilience. They also ensure that members of the broader Catholic community can partake in the cathedral's spiritual revival.
With its spire once again piercing the Parisian sky, Notre Dame is poised to reclaim its role as a global beacon of faith and art.
The cathedral, which previously welcomed 12 million annual visitors, is expected to draw 15 million in its new chapter.
