CBI director-general John Cridland was speaking at the Beyond Paris event in London organised by think-tank, the Green Alliance.
"Over many years, the UK has built up real credibility on climate leadership and low-carbon investment. This is hard won, but easily lost," Cridland said.
"And despite the progress so far, today's investors are more uncertain about the UK's low-carbon future. From the roll-back of renewables to the mixed messages on energy efficiency, these changes send a worrying signal about the UK as a place for low-carbon investment.
"Moreover, this seemingly weakened commitment risks impacting our standing on the global stage, at the exact moment we need to stand up and be counted," he added.
Cridland said the event marks 80 days before final day of the COP21 UN climate conference in Paris. The conference aims to agree a global deal on reducing climate emissions to tackle climate change.
Also speaking at the event was former US vice president and climate activist Al Gore. He described the UK's action on renewables policies as "puzzling".
The UK government has recently announced plans to end support for onshore wind projects by closing the RO support scheme a year earlier than expected.
And energy minister Amber Rudd was also evasive on whether onshore wind would be eligible for future subsidy auctions in the RO-replacement scheme, Contracts for Difference (CfD).
The government has also announced changes to the country's support for solar, the feed-in tariff for small scale renewable energy projects and alterations to the climate change levy.
Last week, analyst firm Ernst and Young (EY) said the recent policy changes have "sentenced the UK renewables sector to death".