The announcement follows strong criticism by US President Donald Trump' s administration, which accused the WHO of being "China-centric", and has started its withdrawal from the UN agency.
The World Health Organization, which faced fierce US criticism over its handling of the coronavirus crisis, has launched an independent panel to review its response to the pandemic.
The Independent Panel for Pandemic Preparedness and Response will be headed by former New Zealand prime minister Helen Clark and former Liberian president Ellen Johnson Sirleaf.
"Through you, the world will understand the truth of what happened and also the solutions to build our future better as one humanity," World Health Organization chief Tedros Adhanom Ghebreyesus said on Thursday at the UN agency's headquarters in Geneva.
At their annual assembly in May, WHO member states agreed to an independent probe into the UN agency's coronavirus response, following repeated US attacks.
US President Donald Trump has accused the WHO of botching its handling of the pandemic and of being a "puppet of China".
The resolution, tabled by the European Union, called for an "impartial, independent and comprehensive evaluation".
It said the investigation should probe "the actions of WHO and their timelines pertaining to the Covid-19 pandemic".
The US on Tuesday formally started its withdrawal from the WHO, making good on Trump's threats to deprive the UN body of its top donor over its management of the pandemic.
Public health advocates and Trump's political opponents voiced outrage at the move.
A divided international community
Tedros hit out at divisions in the international community and warned of severe consequences if this were not rectified.
"Make no mistake: the greatest threat we face now is not the virus itself – rather, it is the lack of leadership and solidarity at the global and national levels," he said.
"We cannot defeat this pandemic as a divided world. The virus thrives on division but is thwarted when we unite."
The novel coronavirus has killed more than 553,140 people since the outbreak emerged in China last December, according to tracking websites.
More than 12.2 million cases of coronavirus have been registered in 196 countries and territories. Of these, at least 7,102,612 are now considered recovered.
"How is it difficult for humans to unite to fight a common enemy that's killing people indiscriminately?" Tedros said.
"Together is the solution, unless we want to give the advantage the enemy, to the virus that has taken the world hostage – and this has to stop."
Performance in past pandemics
The WHO's response to the 2014 Ebola crisis was widely criticised. The pandemic killed some 11,000 people mostly in the West African countries of Guinea, Liberia and Sierra Leone.
Tedros said it was time for honest reflection, and stressed it was important to remain vigilant.
"We're in the midst of this battle. The battle of our lives, and we have to do better, not just now but for the future. Because these threats will never stop and, in all likelihood, they will get worse," he said.
The panel will stage one mission briefing per month to give updates, while it will present an interim report to the next World Health Assembly gathering in November.
Nobel Peace Prize winner Sirleaf said: "I look forward to doing all we can to respond to these challenges that have prevented us from being united in moving forward, not only to address the effects of Covid-19 but to ensure a better health system for all nations of the world."
Clark added: "This assignment could only be described as exceptionally challenging."
Ilona Kickbusch, a global health expert and former WHO head of communications, said that any review had to be credible.
"It has to be seen as a group of people that one can trust, that can start the process, and will probably involve others," she said.