Amazon, BT and supermarket chains Tesco and Marks & Spencer are among more than 100 companies to have voiced their concerns in a letter to Mr Sunak, The Times reported.
US President Joe Biden has put $369 billion of green subsidies on the table while Brussels has set out plans to lead a green manufacturing drive.
Mr Sunak has backed Britain's 2050 net-zero goal but critics have questioned his commitment to the green agenda.
His environment minister, Zac Goldsmith, accused him of being “simply uninterested” in a resignation letter last month.
The government touts Britain as the fastest cutter of emissions in the G7 since 1990 but a watchdog said last week that the UK remains of Europe's most gas-dependent economies.
“We plan to invest billions into the low-carbon economy because we know it is crucial for our future prosperity, and because we know it is the right thing to do for the future of our planet,” the group of 104 businesses was quoted as saying in its letter.
“This is the economic opportunity of the 21st century and we are concerned that without a renewed focus and commitment to delivery from the government, the UK will be left behind.
“We are ready to invest, but we need your leadership and commitment to the green economy – now, more than ever.”
Britain on Tuesday launched a new nuclear power body to oversee a revival in fission in the UK, billed as a way of generating low-carbon power.
However, Mr Sunak has been criticised for keeping in place an effective ban on onshore wind.
As Europe bakes in a summer heatwave, the Met Office said Britain's record 40°C temperatures of last summer could become a regular occurrence thanks to climate change.