HONG KONG—Last year, Chinese policy makers shook up the world’s second-largest economy just as its rebound from the pandemic was starting to wear off, unleashing a flurry of measures to address longer-term economic imbalances—and delivering a short-term hit to business activity.

Now, China’s leaders are hoping that they can put a floor under the economy, which officials said Monday expanded by just 4% in the fourth quarter of last year, the slowest pace since the beginning of the Covid-19 recovery in the second quarter of 2020.