Roberts looked thin and didn’t bother to cover her hair loss with a wig. She wore a wide smile in taking her seat next to co-host George Stephanopoulos on TV’s top-rated morning show.

“I have been waiting 174 days to say this,” Roberts said. “Good morning, America.”

The bulk of the ABC show turned into a celebration of her return as she’s recovering from MDS, a blood and bone marrow disease. President Barack Obama, former Secretary of State Hillary Rodham Clinton and basketball star Magic Johnson all sent taped greetings.

At the studio, ABC boss Anne Sweeney, news division President Ben Sherwood and Katie Couric all stood in the wings watching. When Roberts thanked her nurses on the air, all of the show producers in the control room a floor away stood and applauded. Sherwood delivered a champagne toast on the set after the show went off the air at 9 a.m.

“Can I go home now?” Roberts said, before delivering a tearful thank you to her colleagues.

Bottles of hand sanitizers were kept nearby for people who come into regular contact with Roberts, who must try to avoid contact with others as her immune system builds back up. The plan is for Roberts to work two or three days a week initially and her health will be closely monitored, said Tom Cibrowski, the show’s senior executive producer.

Roberts said after the show that she wasn’t tired and was working on adrenaline. But the bright studio lights affected her eyesight. She said she started having trouble seeing the teleprompters midway through the show.

She has a tough schedule her first week back. She’s expected to co-host the show Thursday and perhaps Friday, tape an interview with first lady Michelle Obama on Friday and fly to California. She’ll participate in Oscars coverage and make an appearance on Jimmy Kimmel’s post-Oscars show. Even her doctor, Gail Roboz, while clearing Roberts’ return, said, “we didn’t exactly have in mind an interview with Michelle Obama and the Oscars this weekend.”

Roberts said her doctors are watching her closely, and they told her to cool it two weeks ago during an appearance in New Orleans.

“I’m not worried about having to be here, or the need to be here,” Roberts said. “I want to be here.”

The return date was important psychologically because it was during Academy Awards coverage last year that Roberts said she felt bone-tired, almost unable to work, and went to the doctor shortly afterward for the blood test that turned up her disease.

She said her hair stylist came up with a wig for her to wear with bangs similar to Michelle Obama’s. But Roberts said viewers had already seen her on the air with her thin layer of hair and she thought a wig would be too distracting.

“It’s freeing, it really is,” she said.

Amy Robach and Elizabeth Vargas largely filled in for Roberts during her absence, although there were occasional celebrity “guest hosts” like Charlie Sheen, Stephen Colbert and Jessica Simpson. The show didn’t miss a beat, not losing a single week to NBC’s “Today” show while she was gone, a development Sherwood admitted was a surprise. An unintended consequence was that her absence enabled an ensemble that also includes Josh Elliott, Lara Spencer and Sam Champion to grow stronger and become more familiar to viewers, he said.

The “Today” show sent a gift basket that “Good Morning America” displayed in its studio, and gave Roberts an on-air welcome.

“She’s looking and feeling great,” said NBC’s Savannah Guthrie. “And I know we’re all really happy for her.”

The return of Roberts, which Sherwood called “a day that we all rejoice,” could also give ABC new momentum in the contest for morning television dominance. NBC’s top anchor, Matt Lauer, is on vacation this week.

“Having Robin back is going to take us to new levels, to new heights,” Cibrowski said.