The currency has tumbled more than 25 per cent in 2022 as scorching inflation and deep concern over the central bank's unorthodox monetary policy have prompted foreign investors to flee the market.
Turkey has been bucking the trend of other central banks that are raising borrowing costs to rein in global inflation.
Şahap Kavcioğlu, the central bank governor, supports president Recep Tayyip Erdoğan's unusual theory that high interest rates cause inflation, while mainstream economists subscribe to the opposite view.
"Instructions may have come down for a cut amid signs growth may be slowing," said Ceyhun Elgin, a professor of economics at Boğaziçi University in Istanbul. "The aim may be to carry things forward, for better or for worse, until the election."
Erdoğan's ruling party has seen its support tumble to historical lows amid widespread unhappiness with the cost of living in Turkey, less than a year before elections. The president is betting that the weak lira will help manufacturers export more goods and cheap credit will boost investment and jobs.
Kavcioğlu, who took the helm at the bank last year, began easing monetary policy in September, cutting rates from 19 per cent. That has unleashed Turkey's highest inflation in a quarter century. Rates, until Thursday, had been unchanged at 14 per cent since December.
In recent weeks, the central bank has recorded a sharp rise in its foreign currency reserves, helped by inflows from governments abroad, according to the finance minister.
This may have encouraged Kavcioğlu to cut rates again, giving the bank more of a buffer if it has to intervene to support the lira, Elgin said. But the bank's coffers remain about $61bn in the red, when liabilities to other banks are accounted for, according to Goldman Sachs estimates.
"With this decision, the central bank of Turkey drops any residual pretence to be targeting inflation and reveals its overarching goal of supporting growth. With inflation at 80 per cent, however, this recipe only spells disaster," Cristian Maggio, head of emerging markets strategy at TD Securities, wrote in a note.
The central bank officially targets inflation of 5 per cent by the end of 2022.
-By Ayla Jean Yackley in Istanbul