Regis Philbin, a star of morning television for a generation, made a surprise announcement at the start of “Live with Regis and Kelly” Tuesday morning, telling viewers that he intended to step down sometime later this year.

The decision will mark the end of one of television’s longest runs on the same show for an individual host — 28 years. Mr. Philbin has shared the show with two chief co-hosts during his run, Kathie Lee Gifford and the current co-host, Kelly Ripa.

Addressing the camera and his studio audience, Mr. Philbin broke into his usual morning banter with Ms. Ripa, to say: “Well, I’ve got one of those announcements to make.” He added that he didn’t “want to alarm anybody” and then declared, referring to the show’s producer, Michael Gelman: “It’s going to happen. The station needs to know and Gelman needs to know and we all need to know. But this will be my last year.”

Mr. Philbin, 79, did not offer any specific reason for his decision other than to say, “There is a time. Everything must come to an end for certain people on camera — for certain old people.”

Mr. Philbin has always been known for his high energy and spontaneous wit, which have made him a favorite not only with viewers but with other professionals in the business. One of his biggest fans, the late-night host David Letterman, has called Mr. Philbin “the best there is” on many occasions.

Mr. Philbin, a native New Yorker, said it had been the “thrill of my life” to come back to New York, where he grew up watching the early days of television, and star in a show of his own. He did not cite a specific date for his departure, but said it would probably take place at the end of the summer or in the fall.

Later in the show, Mr. Philbin clarified that he is not retiring from show business, saying, “I’m not going to retire, I will just be gone.”