The STOXX 600 closed 1.2% up after Bloomberg reported that the two sides were closer to agreeing on the amount of tariffs that would be rolled back in a phase one trade deal.
The report lifted the benchmark from a one-month low hit on Tuesday after U.S. President Donald Trump said a deal might have to wait until after the presidential election next November.
"I don't think people are positioned one way or the other," said Chi Chan, European equities portfolio manager at Hermes Investment Management. "The reason is, every time you get a bit of news the market swings quite violently ... that shows there is nothing particularly baked in."
"It's the marginal buyer that is moving the market."
Financials and industrials led the charge, with planemaker Airbus rising 3.2% after winning an order from U.S. carrier United Airlines.
Further support came from IHS Markit's better than expected final reading on November business activity in the euro zone.
Trade-sensitive German shares were up 1.2%, logging their biggest percentage gain in a month. Chipmakers such as Infineon Technologies and STMicroelectronics gained more than 1.4% after upbeat earnings forecast from U.S. peer Microchip Technology.
Dutch semiconductor company ASML Holding advanced by 2.6% after J.P. Morgan raised its price target on expectations of strong performance in 2020.
French shares gained 1.3% after Trump and French counterpart Emmanuel Macron said on Tuesday that they hoped to smooth out their differences over a digital services tax. Washington has threatened 100% tariffs on French champagne, handbags and other products if France proceeds with the proposed tax on big technology companies.
Luxury stocks such as LVMH, Kering and Hermes firmed by between 0.6% and 1.5%, enjoying some respite after a rough day on Tuesday because of Trump's tariff threat.
A big faller was French telecoms company Orange, which slid 4.7% after traders pointed to disappointment over the firm's dividend outlook.
London shares lagged, rising only 0.4%, partly because of a rally in the pound, which tends to hit heavyweights with international exposure.
By Sruthi Shankar and Susan Mathew