The declaration follows independent reports over the past few years that have found about 1 million Uighur Muslims confined to concentration camps, subject to torture and forced sterilisation.
There have also been reports of authorities seeking to eradicate their religion and culture.
Today the Chinese Embassy in Wellington said the declaration had "total disregard" of China's position and was a "groundless accusation on China over human rights abuses".
"This move grossly interferes in China's internal affairs, and runs counter to international law and basic norms governing international relations. The Chinese side deplores and firmly opposes such action."
The statement mirrored similar comments China has made in response to other countries raising concerns about the treatment of Uighur.
The United States has declared genocide was occurring, under former president Donald Trump and President Joe Biden.
Parliaments in the Netherlands, Canada and the United Kingdom had also voted to pass similar motions condemning the abuse as "genocide".
The embassy spokesperson said Xinjiang-related issues were about "countering violent terrorism, radicalisation and separatism" through "deradicalisation through education and vocational training".
Xinjiang-related issues were "purely China's domestic affairs where there's no place for foreign interfere".
Pressuring China over this would "go nowhere but to harm the mutual trust between China and NZ".
"We hope the NZ Parliament will do more to strengthen the friendship and co-operation between our two countries and people, not the other way around," the spokesperson said.
Prime Minister Jacinda Ardern said China's response was "not unexpected".
"There have been a number of statements made globally on the situation of the Uighur, and unlike many others there were no abstentions. It was supported by all of Parliament, while others have had abstentions and demonstrates the feeling of parliamentarians over the issue.
"It was in line with other statements that there is credible evidence of human rights abuses there."
Speaking in the House today, van Velden questioned Foreign Minister Nanaia Mahuta over communications the Government had with China over the declaration.
Finance Minister Grant Robertson, speaking on behalf of Mahuta who was absent, said it should be "no surprise" China had engaged with New Zealand since the declaration.
Robertson said New Zealand would continue to raise concerns about "grave reports of severe human rights abuses" and call for "unfettered access" by United Nations investigators.
He said there had been no engagement with Chinese authorities around using the term "genocide".
Questioned around the original wording of the motion and Labour's request to have "genocide" removed, Robertson said their concern was around the concept as under international law.
"It requires significant investigation, which New Zealand rarely uses, so the discussion around it related specifically to that."
Uighur Solidarity Aotearoa spokesman Sam Vincent said Parliament failing to refer to genocide in the motion sent a "clear message to the international community that money is more important to our government than human rights".
New Zealand Uighur Rizwangul NurMuhammad, whose brother was imprisoned in Xinjiang for claimed separatist activities, said not only should New Zealand be declaring genocide but as a Kiwi she deserved more consular assistance to see her family again.
"The Government may again claim that my brother is a Chinese national and that it is a domestic matter, but they need to realise that as a New Zealander my basic human rights such as having a free and open communication with my mother and family is being infringed upon.
"I want to see my family is living a safe and happy life, and enjoying their human rights including having passport and freedom of movement. My brother is innocent, and he must be released immediately and unconditionally."
What MPs said about motion
Speaking on behalf of Labour about the motion yesterday, Mahuta said Ardern, who was not present during the debate, had raised the concerns directly with the Chinese government, and called on China to respect the rights of the Uighur and other ethnic minorities.
Although the Government had not formally designated the situation as genocide, it was "not due to lack of concern".
"Genocide is the gravest of international crimes and a formal legal determination should only be reached following a rigorous assessment on the basis of international law.
"New Zealand has not previously made an independent determination of genocide, we relied upon judicial findings of genocide in the case of Cambodia, Rwanda and of course the Holocaust."
The Government would continue to work with international partners and the United Nations to push for an investigation and abuses to end, Mahuta said.
Act, the Green Party and te Pāti Māori (Māori Party) all asserted their support for the original motion using the term "genocide".
Van Velden said having to dilute and soften the motion to gain the acceptance of the governing party was "intolerable".
National's Todd Muller commented on the depth of the relationship with China, which meant criticising where necessary.
"Neither do we shirk from uncomfortable conversations and today this House speaks in one voice with our concerns about severe human rights abuses in China."
Green MP Golriz Ghahraman called for a stronger wording of the motion, and criticised both major parties for bringing up trade when debating using the term genocide.
"I was deeply disappointed to hear leadership from both major political parties refer to trade as a consideration for them when they were discussing whether or not they would allow a motion using the word genocide when they were talking about the mass torture, extrajudicial detention, sterilisation and slavery of some one million people.
"The Green Party unequivocally condemns the grave atrocities being suffered by the Uighur minority in Xinjiang province and other cultural and linguistic minorities at the hands of the Chinese government."
Te Pāti Māori co-leader Debbie Ngarewa-Packer said they stood in solidarity with all indigenous and oppressed peoples right around the world.
"Ethnic violence starts with racism. We should use this place to lead and stamp it out."
