It will be the first time Belgium features on the championship calendar, with the Ypres-based event scheduled for Nov. 19-22 as the eighth round of a reduced and rescheduled season.
Japan had been due to make its return after a 10-year absence but organisers said the event had been called off due to border entry restriction policies imposed by the government in response to the pandemic.
Belgium will be the 34th country to hold a round of the championship and the rally's final leg will focus on the Spa-Francorchamps circuit, with the final Power Stage featuring the Eau Rouge/Raidillon section of the Formula One track.
It will be a home race for Hyundai's Thierry Neuville, currently third in the championship.
Simon Larkin, senior director of events for the WRC promoter, said the rally would provide a fitting finale to the season.
"Its tricky mix of narrow asphalt lanes and big ditches lining the roads, allied with some stages in the dark and the potential for mixed weather, will provide plenty of thrills and spills for fans," he said.
The next round of the championship is in Estonia, which makes its first appearance on the calendar on Sept. 4-6. (Reporting by Alan Baldwin, editing by Christian Radnedge)