The comedian abruptly cancelled Colbert Report tapings last week, leading to speculation that his 91-year-old mother had suddenly taken ill.
Colbert appeared to confirm the rumours on Twitter last Friday, writing: "My family and I would like to thank everyone who has offered their thoughts and prayers. We are grateful and touched by your concern."
The Colbert Report returned to the air last night with the host addressing his absence in the opening of the show.
Colbert made light of the media's coverage of his hiatus by insisting that he had not been censored by the FCC and also denied claims he had cosmetic surgery. The comedian wrapped up the segment with a special message to Lorna, who is the mother to eight sons and three daughters.
"Oh, one more thing. Evidently having 11 children makes you tough as nails," he said, adding: "Confidential to a lovely lady."
The Colbert Report continues tonight at 11.30/10.30c on Comedy Central with guest Robert Kagan.
Watch Stephen Colbert's return to the air below: