He paid tribute and offered words of sympathy to the victims of the February 22 natural disaster which struck New Zealand's second city.
But the crisis currently engulfing Japan was not far from the Prince's mind, and during his speech he expressed his condolences to the troubled country.
"We honour the memory of those who did not survive," the royal said at the national memorial service.
He said the torment suffered by Christchurch residents gave them an insight into Japan's current situation, where thousands have been killed by last Friday's earthquake and tsnuami.
"This community... can appreciate the full horror of what is unfolding in Japan.
"Our thoughts and prayers are with them too."
The Prince, who was presented with a Maori cloak, told an emotional crowd that the world had watched Christchurch's response to the earthquake with admiration.
"You are an inspiration to all people. In the last two days, I've heard tales of great tragedy, but also of extraordinary bravery and selfless courage," he said.
William, New Zealand Prime Minister John Key and Australian Prime Minister Julia Gillard stood with their heads bowed as members of the crowd wept and hugged one another.
The 6.3 magnitude tremor that hit Christchurch claimed over 180 lives and flattened much of the city.
During his five-day tour around disaster areas in Australia and New Zealand, William visited the city on Wednesday to witness the damage first-hand and hear personal stories.