Pet owners spend £78 million extra per year on gas and electricity bills.
Research by Energy Saving Trust revealed 43% of them admitted they leave the heating on during the day to keep pets warm.
Around 26% also said they turn on the radio while 15% admitted they leave the TV on to keep their pets company.
The charity warns that leaving the heating on all day could add up to £140 a year on energy bills.
Philip Sellwood, Chief Executive at Energy Saving Trust said: “We just want to make sure that everyone is aware of the facts so they can heat their home comfortably and affordably.
“These creature comforts do come with a cost and heating represents the greater portion of this expense. On average we spend more than half of our energy bills on heating so to spend more money when we’re not there for pets that have fur coats isn’t essential. We are urging householders to programme their heating to reduce energy use and save money.”