The Broadcasting Standards Commission has upheld 30 viewers' complaints about presenter Jonathan Ross swearing during Comic Relief Red Nose Night.
Ross used the "f-word" during Comic Relief Red Nose Night
The watchdog says it was unacceptable for Ross to use the 'f-word' on BBC One, even after 2230, because many children were still watching.
Several programmes were criticised in a BSC report published on Thursday.
At the end of the year, the commission will be replaced by the new communications regulator, Ofcom.
The BBC told the commission it was extremely sorry viewers had been offended.
It also apologised for swearing by a guest on Ross's BBC Radio 2 show.
The report also criticised Channel 4 for an episode of the Ali G show screened in April, in which comic Sacha Baron Cohen's latest character, Bruno, imitates the physical symptoms of disabilities.
The camp fashion pundit was shown asking industry figures whether they would use disabled models.
Channel 4 said it was intended to highlight fashion's obsession with the perfect body and reluctance to use models who might be perceived as "less than perfect".
But, responding to viewers' complaints, the report said: "The language used to refer to people
with disabilities, in addition to the mimicking of their physical symptoms, exceeded acceptable boundaries."
The report also criticised swearing on consumer programme Watchdog.
The BBC said a swear word had been used without bosses' permission.
The report also says repeated swearing on Channel 4's 100 Worst Britons programme was "beyond acceptable boundaries".
The channel said swearing had been bleeped out until the 2100 watershed.