Thanks to taped reality TV shows, he also remains as a contestant to become Donald Trump's next "Celebrity Apprentice."
At the end of Sunday's episode, an announcer acknowledged Michaels' illness -- published reports say he is bleeding at the base of his brain stem -- and said everyone at NBC "wishes Bret Michaels a speedy recovery."
A report from Michael's from doctors is expected this week. The 47-year-old rocker's site doesn't say where Michaels is hospitalized.
"Please remember Bret is, and always has been, a fighter and survivor and is under the best medical care possible," the post added.
Michaels' New York-based publicist, Joann Mignano, confirmed on Friday a report on People magazine's website that said the former Poison frontman was rushed to intensive care late Thursday after a severe headache. Doctors discovered bleeding at the base of his brain stem, the report said.
On Donald Trump's competitive reality show, Michaels, who is competing to raise money for his charity, diabetes research, has served as one of the season's most outspoken celebrities and has so far avoided being fired in the boardroom.
Michaels had an emergency appendectomy April 12 after complaining of stomach pains before he was scheduled to perform at Sea World in San Antonio. Michaels later wrote on his website that although the surgery "has taken its toll," doctors expected him to make a full recovery.
Before joining the third season of "The Celebrity Apprentice," Michaels starred as the lothario on VH1's lusty reality dating series "Rock of Love" from 2007 to 2009. For three seasons, Michaels searched for the women of his dreams amid a sea of implants, tattoos and thongs. He also served as a judge on the fifth season of the USA singing competition "Nashville Star" in 2007.