More than 25 bishops and 800 priests were in attendance at the service celebrated by the Bishop of Tarbes and Lourdes, Jacques Perrier and the Archbishop of Marseille Bernard Panafieu.
The mass took place in a field opposite the Massabielle shrine where the mother of Jesus Christ is said to have first appeared in a vision to Bernadette Soubirous on February 11, 1858.
Simultaneously at the Vatican in Rome a rib belonging to Soubirous was ceremoniously conveyed to Saint Peter's Basilica to mark the anniversary.
The relic was conveyed in solemn procession up the main thoroughfare between Rome's Tiber River and Saint Peter's Basilica, escorted by about 15 Italian police mounted on white horses.
Soubirous became a nun after her visions, and was canonised by the Roman Catholic Church as Saint Bernadette in 1933.
The town of Lourdes in southwestern France is one of the main pilgrimage sites for the Church, attracting millions of believers from around the world who venerate the Virgin.
Many who are suffering make the trip in hope of being cured by the supposedly miraculous waters of a spring at the site of the visions.
Accompanied by a 30-member choir, readings for the mass were given in several languages, including English, Spanish, German, Italian, Portuguese and Polish.
"Coming here is to have one's belief replenished, in a world of mistrust, hostility and indifference," said Perrier in his homily to the pilgrims.
"Lourdes is also perhaps like a school for prayer -- a place where it is easy, even natural, to pray because one senses it is expected," he said.
After Perrier finished mass, bells from all the churches in Lourdes rang out in unison. A torchlight procession in honour of the Virgin Mary was scheduled for the evening.
The year-long celebrations began on December 8, 2007 and will run through until December 8, 2008. They commemorate a total of 18 visions believed to have been seen by Soubirous between February and July of 1858.
For the Catholic Church, Soubirous' visions confirmed the dogma of the Immaculate Conception -- proclaimed four years later by Pope Pius IX -- which declares that Mary was "without sin" when Jesus Christ was conceived.
Pope Benedict XVI is expected to take a pilgrimage to Lourdes sometime in September.
In December, the Vatican announced the pope would grant indulgences for a limited time to pilgrims who visit Lourdes for the 150th anniversary.
In the Catholic Church, indulgences are remittances of suffering for sins. In order to go to heaven, it is believed one must 'repair' the harm committed on earth before death.
Soubirous herself died in 1879, aged 35, and is buried at Nevers, central France.