In a blog post, the 70-year-old said he'll take a "leave of presence."
"I am not going away," the ailing Pulitzer Prize winner wrote in a note posted late Tuesday. "My intent is to continue to write selected reviews but to leave the rest to a talented team of writers. ... What's more, I'll be able at last to do what I've always fantasized about doing: reviewing only the movies I want to review."
The veteran critic battled cancer in his thyroid and salivary glands and lost the ability to speak and eat during previous surgery, which also left him with a facial disfigurement.
Ebert said the cancer recurrence was discovered after a "painful fracture" that made it difficult for him to walk. He hospitalized late last year with a hip fracture.
"It really stinks that the cancer has returned and that I have spent too many days in the hospital," he wrote.
In addition to the select movie reviews he'll write, Ebert said he also plans to spend time writing about his own illness.
"I may write about what it's like to cope with health challenges and the limitations they can force upon you," he said. "So on bad days I may write about the vulnerability that accompanies illness. On good days, I may wax ecstatic about a movie so good it transports me beyond illness."
Ebert penned more than 300 reviews last year. He also said he plans to relaunch his website and roll out several other projects later this year.
Ebert began reviewing films for the Chicago Sun-Times in 1967 and marked his 46th anniversary at the paper on Wednesday. He was the nation's foremost movie critic on television on shows such as "Sneak Previews" and "At the Movies."