HONG KONG—China’s President Xi Jinping received lavish praise and a new leadership title from his top Communist Party lieutenants, the clearest signal yet that he retains a firm grip on power despite policy setbacks in the past year.

During a two-day meeting that ended Friday, chaired by Mr. Xi, the party’s 25-member Politburo hailed his policies as visionary and described him as the renmin lingxiu, or “people’s leader,” a designation that directly echoes an accolade most closely associated with Communist China’s founder Mao...