"The radio DJ flew into a rage after gossip columnist Zoe Griffin said her fiancé, Luke Worrall, was stupid," Witnesses claimed.
Griffin is said to have taunted Osbourne, 24, that Worrall, 19, did not know what an earthquake was.
The incident occurred in the Punk nightclub, a favourite celebrity haunt, in August.
Osbourne went with her lawyers to a central London police station voluntarily earlier this month.
A Met spokesman said: 'We can confirm a 24-year-old woman attended a central London police by appointment on 2 January.
'She was arrested for common assault relating to an alleged incident in Soho in the early hours of 29 August 2008.'
“She has been bailed until a date in March.”
Kelly was released on bail until March.
Kelly recently revealed she would 'do anything for her man'
Kelly told Closer magazine: 'I’ve never been this mushy with anybody ever before, but this time I can’t help it. He’s perfect. Everything about him is brilliant.
'I’m happy. I love him and I’d do anything for him.'
But the couple haven't been able to spend much time together recently.
'He’s busy working – but we’re constantly on the phone to each other. 'I’m stuck in LA and Luke’s not always here,' she said.
In a separate incident, Los Angeles police are investigating Osbourne’s mother Sharon for allegedly attacking a contestant on the reality show Rock of Love: Charm School last month.
Megan Hauserman, 26, claims Sharon, 56, pulled her hair and scratched her until she was pulled away and restrained by security staff.
Sharon reportedly 'lost it' after Hauserman called her heavy metal husband Ozzy a 'brain-dead rock star'.
Three years ago, Sharon Osbourne threw two glasses of water over X Factor co-judge Louis Walsh when he panned one of the competing acts, Journey South.