The country's target to reach net zero emissions by 2050 will require changes to the way people eat and travel, as well as how electricity is produced.
"This decrease in 2023 is primarily due to a reduction in gas demand from the electricity supply and buildings and product uses sectors," the Department for Energy Security and Net Zero (DESNZ) said.
Total greenhouse gas emissions were estimated at 384.2 million tonnes of carbon dioxide equivalent in 2023.
The electricity sector, which makes up around 11% of Britain's GHG emissions, recorded the biggest drop at 41.1 MtCO2e compared with 51.9 MtCO2e in 2022.
A rebound in French nuclear power output in 2023 meant Britain was able to import more electricity, cutting the need for homegrown fossil fuel power production, while electricity demand also fell, DESNZ said.
Gas power generation in Britain fell by 21.1% in 2023, the data showed.
In the buildings and product uses sector emissions fell by 6.2% "largely as a result of reduced demand for heating due to high energy and other costs", DESNZ said.
Energy prices for most UK households hit record highs at the end of 2022 despite support from the government and did not begin to fall until July 2023.
Emissions from the industrial sector fell by 8% mainly due to reduced fuel consumption in the iron and steel industries.
In the domestic transport sector, which includes road travel, aviation and shipping, emissions were down by 1.4%.
Emissions of carbon dioxide (CO2), the main greenhouse gas, were estimated at 302.8 million tonnes, 6.6% lower than in 2022.
