The oil-production cut is the biggest from the group collectively known as OPEC+ since April 2020, signaling its intent to keep prices high after enduring seven years of a relatively subdued market, oil-industry analysts said.

After surging above $100 a barrel in the first six months of the year over Russia’s invasion of Ukraine, oil prices have fallen 32% over the past four months on global economic worries, with international benchmark Brent crude dropping below $83 a barrel for the first time since January. Brent rose 0.6% to $92.38 on Wednesday, after having risen steadily on expectations of a production cut in recent days.

Before the meeting, OPEC+ members framed any decision coming out of the meeting as a technical response to a flagging global economy, especially in China, where Covid-19 restrictions have hurt oil demand.

But analysts said, and in private OPEC+ delegates agreed, that the move would be a big win for Russia, which has lost about a million barrels a day of oil production since the beginning of the war in February. On Dec. 5, Russia faces the prospect of a European Union oil embargo and the G-7 price cap, which threaten to further cut into its sales.

The OPEC+ production cut will limit Russia’s loss of market share, said delegates, who acknowledged it represented an unprecedented effort by the world’s biggest oil producers to collectively help Russia with the political and economic problems caused by the war in Ukraine.

Still, participants said their interests would be well served by the decision by boosting the revenue their petrostates need.

Write to Benoit Faucon at benoit.faucon@wsj.com and Summer Said at summer.said@wsj.com