Tests run on the remains of a limestone cave in the Church of the Holy Sepulchre in Jerusalem have dated the tomb to around 345 CE.
That makes it 1,700 years old.
The scientific tests on the shrine were the first of their kind carried out on what the faithful believe to be the resting place of the Christian Messiah.
The tomb itself had not been opened in centuries and was previously thought to have first been built during the time of the Crusaders.
But experts, according to National Geographic, have now said the tomb was originally built 17 centuries ago.
Antonia Moropoulou, chief scientific coordinator of restoration works at the site, said the testing was consistent with historical beliefs that the Romans built a monument at the presumed tomb during the era of Constantine the Great, circa 326.
“This is a very important finding because it confirms that it was, as historically evidenced, Constantine the Great responsible for cladding bedrock of the tomb of Christ with the marble slabs in the edicule,” said Moropoulou, a specialist in preservation from the National Technical University of Athens.
The dating of the mortar shows historical continuity at the site, stretching through the Byzantine era, the Crusades, the Renaissance period and beyond, she said.
The vault is widely believed to be the site of Jesus' crucifixion, burial, and resurrection, referred to in the Bible as Calvary or Golgotha.
An archaeological study on the site last year found that the tomb had never been moved.
While the New Testament says Jesus died either in 30 or 33 CE, historical accounts suggest that Romans located and enshrined the tomb in 326 CE.
The date corresponds to the rule of Constantine I, the Roman emperor who converted to Christianity and declared it the official religion of the empire.
From this point it became more common to build large monuments to Christ.
The tomb was destroyed and subsequently rebuilt in the year 1009, prompting historians to doubt whether the Church of the Holy Sepulchre was the same burial site discovered by the Romans.
However, the latest scientific tests, carried out for over a year by the National Technical University of Athens, suggest otherwise.
Researchers used a technique called optically stimulated luminescence.
It determines how recently quartz sediment in samples from the tomb's mortar were exposed to light.
In March, the newly restored shrine surrounding the tomb was unveiled following months of delicate work.
In October 2016, perhaps the most dramatic moment in the renovation occurred when the cave thought to be the tomb of Jesus was opened for the first time in centuries.
And in December, scientists were amazed to discover, beneath marble cladding that covered a 1555 burial bed, a far older broken marble slab engraved with a cross.
The Greek Orthodox, Armenian and Roman Catholic denominations share custody of the church, but disputes between the three had led to renovations being delayed for decades.
National Geographic's documentary The Secrets of Christ’s Tomb: Explorer Special will be aired on the channel on Sunday December 25.
