A handful of priests from different Christian denominations stood watch as the door to the church in the Israeli-occupied West Bank was opened, an AFP photographer reported.
Once inside, the head of the Greek Orthodox Church in Bethlehem, Bishop Theophylactos, kissed an icon while a priest sprayed holy water in the grotto of the church, where Christians believe Christ was born in a manger.
The church had been closed since March 5 when an outbreak of COVID-19 was detected in Bethlehem.
Initially only 50 people will be allowed in the church at one time and visitors must wear face coverings and observe social distancing, a joint statement from the churches that control the site said.
Kissing or touching the stones, including in the grotto where Christians believe Jesus was born, will be forbidden.
The Bethlehem outbreak began with a group of Greek tourists who visited the city, including the Church of the Nativity, prompting church authorities to sterilise the site.
The Palestinian government swiftly took measures to prevent the spread of the disease and in recent weeks few new cases have been reported in the West Bank.
On Monday, Palestinian prime minister Mohammed Shtayyeh announced an end to the lockdown.
Separately, in Jerusalem the Church of the Holy Sepulchre built on the spot most Christians believe Jesus was crucified and then resurrected, has partially reopened in recent days.
The main door to the church remains closed to prevent overcrowding, but groups of worshippers can enter in coordination with the Christian denominations that control the site, a church official said.