The Blue singer is accused of striking Samantha Miller, 25, as they drove through the West End.
Officers later arrested Lee, 27, at his home in Bromley, south London.
He strenuously denies the allegations.
'Lee 100% denies common assault,' his spokesman tells The Sun. 'He'll be fighting these charges.'
Lee is due at a court in Westminster next week.
He and Samantha - who met on MySpace in 2006 - are parents to Rayn, 1.
Where to next?
- Information on domestic violence
- Celebrity mugshots