It received 25,257 complaints after Roxanne Pallett claimed housemate Ryan Thomas had physically abused her on Celebrity Big Brother.
Thomas, who went on to win the Channel 5 show, was accused of punching her in an episode on 30 August.
Many viewers defended the Coronation Street actor as play-fighting and criticised Pallett for trivialising domestic abuse.
The former Emmerdale actress, who slept in a spare bedroom after claiming she was uncomfortable sleeping in the same room as Thomas, decided to leave the house on 1 September. Thomas was later given a formal warning.
In an interview with host Emma Willis two days later, Pallett apologised to Thomas for making a “horrible mistake” before saying she was the “most hated girl in Britain”.
Viewers voiced offence and concern at Pallett’s claims and the way the situation was handled by the show.
Ofcom will examine whether “appropriate information” was shown by Channel 5 which may have assisted “in avoiding or minimising offence” to viewers.
An Ofcom spokeswoman said: “We are investigating whether this programme broke our rules on offensive content.”
The watchdog is also investigating the Loose Women panel’s treatment of Kim Woodburn, after receiving 7,900 viewer complaints.
The former How Clean Is Your House? presenter clashed with Coleen Nolan and later walked off the set in tears.
Woodburn was invited on the panel show by ITV bosses for a “reconciliation” with Nolan after the women previously argued on an earlier series of Celebrity Big Brother.
Viewers accused Nolan and other members of the panel, which included Linda Nolan, Janet Street-Porter and Linda Robson, of “ganging up” on Woodburn.
A statement posted on Nolan’s Twitter account on 6 September said she was taking a break after being subjected to a “horrifying torrent of online abuse”.
It also said the singer’s words and actions had been misrepresented.