The ECB's governing council confirmed what policymakers had been saying since the summer. They will stop expanding quantitative easing (QE) from the end of December — when bond purchases will fall from 15 billion euros a month to zero.
It marks a historic moment for the central bank, as President Mario Draghi dismantles one of his most contentious policies.
In winding up its massive bond-buying program, the ECB said it planned to spend cash from maturing bonds to purchase additional debt.
These purchases are designed to keep borrowing costs down through to sometime in 2021.
In theory, the open-ended timeline should allow policymakers to push back the date at a relatively low cost to credibility if the economy falters.
The ECB's asset purchasing program — under which the bank bought more than 2.6 trillion euros ($2.9 trillion) — was introduced in March 2015 in a bid to rescue the euro zone economy from deflationary forces and rebuild confidence.
The measures are widely credited to have helped revive the 19-member currency bloc after a double-dip recession and the residual effects of the European debt crisis.
"With the most prominent crisis-fighting measure of the ECB now almost back in the toolbox, the big question is, what will be next?" Carsten Brzeski, chief economist at ING, said in a research note published Thursday.
"It seems as if the ECB wants to keep as many cards as possible close to its chest," Brzeski said.
The central bank's decision to end QE after nearly four years is thought to symbolize the end of crisis-era policies in the euro zone, despite coming at a difficult time for Europe.