Many global companies pay no attention to how their supply chains are damaging forests, Prince Charles warned in a speech at the UN climate talks in Paris.
The Prince of Wales said there was "no Plan B" for climate change if nothing was done about deforestation during his second address to the summit.
He called for large-scale restoration of forests and warned that the world would need more as "all the horrors" of global warming started to bite.
"There can be no room for failure," he told the audience which included King of Sweden, Carl XVI Gustaf.
Protecting forests from being cut down is a key part of tackling climate change, he said.
While some companies had taken steps to transform their supply chains so they did not damage forests, he urged a redoubling of efforts to ensure a shift in global markets.
It is very simple: we must save our forests, for there is no Plan B to tackle climate change or many of the other critical challenges that face humanity without them. Encouraging though the progress made to date has been, it remains the case that many of the world's largest companies - and their financial backers - pay scant, by which I really mean no, attention to the deforestation footprint of their supply chains.
All companies should be committed to stopping destruction of forests, with zero net deforestation becoming the norm rather than the exception, he added.
Preventing the destruction and degradation of forests is a key part of tackling climate change, as the UN estimates the loss of around 12 million hectares a year is responsible for around 11% of global greenhouse gas emissions.