A long-term host for Trebek, who died of cancer on Nov. 8, will be named later.
"By bringing in familiar guest hosts for the foreseeable future, our goal is to create a sense of community and continuity for our viewers," the show's executive producer, Mike Richards, said.
The show is in its 37th year of syndication, and Trebek was its only host since the game returned to the air in 1984. It is still airing shows that Trebek filmed before his death.
Richards said that "Jeopardy!" will air repeat episodes for the holiday weeks beginning Dec. 21 and 28, meaning Trebek's final week of shows will air starting Monday, Jan. 4.
Jennings' episodes begin on Jan. 11.