The euro zone's central bank had previously said rates would stay at their current record-low levels until the end of this year, although investors have not been expecting any rate change for years to come.
The European Central Bank pushed back the timing of its first post-crisis interest rate hike on June 6 and said it would continue paying banks to lend to households and businesses as the outlook for global growth darkens further.
"The Governing Council now expects the key ECB interest rates to remain at their present levels at least through the first half of 2020, and in any case for as long as necessary," the ECB said in a statement.
The euro zone's central bank had previously said rates would stay at their current record-low levels until the end of this year, although investors have not been expecting any rate change for years to come.
In addition, under the ECB's third Targeted Longer-Term Refinancing Operation (TLTRO III) banks will be able to borrow from the central bank at 10 basis points above the average rate applied in the Main Refinancing Operations, currently set at zero, over the life of the loan.
And they could even get paid for lending if they pass on the cash.
"For banks whose eligible net lending exceeds a benchmark, the rate applied in TLTRO III will be lower and can be as low as the average interest rate on the deposit facility prevailing over the life of the operation plus 10 basis points," the ECB said.
The ECB has so far refrained from taking bolder steps, such as cutting rates or restarting its massive bond purchases, maintaining a recovery in inflation towards its target of just under 2 percent had simply been delayed, not derailed.
Attention will now shift to President Mario Draghi's news conference at 1230 GMT, in which he will unveil the ECB's new forecasts for growth and inflation in the euro zone.
With Wednesday's decision, the ECB's rate on bank overnight deposits, which is currently its primary interest rate tool, remained at -0.40%.
The main refinancing rate, which traditionally determined the cost of credit in the economy, remained unchanged at zero percent while the rate on the marginal lending facility -- the emergency overnight borrowing rate for banks -- stayed at 0.25%.
