Her visit would include a stop in the remote western region of Xinjiang, where activists say one million Uighurs have been held in mass detention, she told the Human Rights Council.
China rejects accusations of abuse, describing the camps as vocational centres designed to combat extremism, and in late 2019 it said all people in the camps had "graduated".
Bachelet, speaking by video message to the Geneva forum, made no reference to her long-awaited report on alleged abuses against Uighurs.Â
Her office began gathering evidence three and a half years ago and in December, her spokeperson had promised its release within weeks.
Her advance team would leave in April to prepare the visit - the first to China by a UN High Commissioner for Human Rights since Louise Arbour in 2005.
Chen Xu, China's ambassador to the UN in Geneva, told the forum that freedom of expression was fully protected in his country, but added: "Freedom of expression can never be a pretext to make (put) anyone above the law."
Chen said: "We welcome the High Commissioner's visit to Xinjiang in this May. And China will work together with (her office) to make good preparation for this visit."
Nearly 200 activist groups swiftly issued an open letter demanding that Bachelet publish her findings "to send a message to victims and perpetrators alike that no state, no matter how powerful, is above international law or the robust independent scrutiny of your office".
"We have been concerned by the relative silence of your office in the face of these grave violations," said the groups including Amnesty International, Human Rights Watch and Chinese Human Rights Defenders.
US Secretary of State Antony Blinken, UK Foreign Secretary Liz Truss and Turkish Deputy Foreign Minister Faruk Kaymakci last week voiced concern about the treatment of Uighurs in Xinjiang.
Blinken said at the time: "In China, the government continues to commit genocide and crimes against humanity in Xinjiang against predominantly Muslim Uighurs and other minority groups, and we urge the High Commissioner to release without delay her report on the situation there."
UK ambassador Simon Manley told Reuters on Tuesday: "We welcome any effort to shed light on the systemic violations of human rights in Xinjiang. As we have consistently made clear, the High Commissioner must be granted fully unfettered access to the region that allows her to conduct an accurate assessment of the facts on the ground. We look forward to her report into the situation."
