Mr Erdogan's offer came as he flicked the switch on Turkey's first delivery of natural gas — extracted from a reserve discovered in the Black Sea — to an onshore plant.
Elections are set to take place on May 14 but opinion polls show Mr Erdogan could lose power after two decades.
The announcement came at a ceremony that marked the government's latest attempt to showcase large energy and infrastructure projects in the run-up to the polls.
“We will provide free natural gas for household consumption up to 25 cubic metres monthly for one year,” Mr Erdogan said at the inauguration of the onshore natural gas port in the northern province of Zonguldak.
The free gas will start from next month, he said.
Natural gas was first discovered at the Sakarya field off the coast of Zonguldak in 2020, and at the Caycuma-1 field next to it last year, with total volume having since been estimated at 710 billion cubic metres (bcm).
Turkey, which has little oil and gas, is highly dependent on imports from Russia, Azerbaijan and Iran, as well as liquefied natural gas imports from Qatar, the US, Nigeria and Algeria.
Domestic natural gas production mainly in the Thrace region accounted for less than 1 per cent of Turkey's 60 bcm national consumption in 2021, according to EPDK energy regulator data.
Mr Erdogan said Turkey's Black Sea gasfields would initially produce 10 million cubic metres of gas per day.
Production will be increased to 40 million cubic metres of gas a day in the coming period, he said.
“When we reach full capacity, we will be able to meet approximately 30 per cent of domestic consumption yearly from here,” he said.
The presidential and parliamentary polls represent the biggest electoral challenge for modern Turkey's longest-serving leader, after a cost-of-living crisis and the handling of February's massive earthquake has eroded his support.
Opposition candidate Kemal Kilicdaroglu is currently leading in opinion polls.
The government has unveiled a series of large infrastructure and defence projects ahead of the vote.
Next week, Mr Erdogan is set to inaugurate Turkey's first nuclear power reactor built by Russia's state energy company Rosatom.