The Al Noor mosque was taken over by police for investigations and security reasons after alleged gunman Brenton Tarrant attacked Muslims gathered there and at a smaller mosque for Friday prayers, killing 50 people.
But it was handed back to the local Muslim community on Saturday and began allowing small groups onto its grounds around midday.
"We are allowing 15 people at a time, just to get some normality," said Saiyad Hassen, a volunteer at Al Noor.
"I'm not in a place to say when it is going to (fully) reopen."
Mosque officials were not immediately available for comment.
The attacks have shocked a country of 4.5 million known for its tolerance and prompted global horror, heightened by Tarrant's cold-blooded live-streaming of the massacre.
New Zealand came to a standstill on Friday to mark one week since the massacre, with the Muslim call to prayer broadcast across the country followed by two minutes of silence in honour of those slain.
Nationwide ceremonies saw poignant scenes of Kiwis embracing Muslims, and of non-Muslim New Zealand women donning makeshift Islamic headscarves in solidarity.
A day earlier, the country outlawed the military-style rifles used in the assault with immediate effect.
Al Noor had remained closed partly so that workers could repair bullet-pocked walls and clean blood-spattered floors, and on Saturday there was a little obvious indication of what took place there.
No bullet holes could be seen and walls appeared to have been freshly painted. Inside, emotional Muslim visitors stood quietly as bright sunlight streamed through windows.
There were also other signs of Christchurch moving forward from the trauma, with children seen playing cricket at a park across from the mosque and previously scheduled sporting events expected to go ahead this weekend.
The Al Noor mosque was taken over by police for investigations and security reasons but it was handed back to the local Muslim community on Saturday and began allowing small groups onto its grounds around midday.