In a statement, Pegasus Health said its Madras Street facility was full and it felt it was clinically unsafe to accept any more patients until the number of people waiting to be seen reduced.
The surgery closed just after 9pm until 11:45pm.
Pegasus Health general manager patient and provider services Lisa Brennan said patients were provided with information about where to seek care until the surgery returned to normal operating.
"We worked with other providers and Christchurch Hospital Emergency Department to ensure those who needed care immediately were able to be seen."
She said it was the first time high demand had closed the 24-hour surgery.
"It was the best way to ensure we were providing safe quality care and will remain an option while patient numbers remain high," Brennan said.
