Jennings, a former "Jeopardy!" champion, is the first in a rotating cast of guest hosts that are continuing the show. He joined the show in September as a consulting producer.
"No one will ever replace the great Alex Trebek, but we can honor him by playing the game he loved," Jennings said.
"Welcome to 'Jeopardy!' You know, sharing this stage with Alex Trebek was one of the greatest honors of my life. Not many things in life are perfect, but Alex did this job pretty much perfectly for more than 36 years, and it was even better up close.
We were dazzled by his intelligence, his charm, his grace, really, there's no other word for it. Like all Jeopardy! fans, I miss Alex very much, and I thank him for everything he did for all of us. Let's be clear: No one will ever replace the great Alex Trebek. But we can honor him by playing the game he loved."
NewsletterSIMPLY PUT - where we join the dots to inform and inspire you. Sign up for a weekly brief collating many news items into one untangled thought delivered straight to your mailbox.