He accepted that he made contact with Sophie Cahill's face when he flailed his arms during a scuffle.
But he told Croydon Magistrates' Court it was accidental.
Ms Cahill, of Cwmbran, Torfaen, said Mr Bowers had hit her in the face, bloodying her nose, and had pulled her hair and squeezed her throat.
Asked by John Blandford, defending, if it was true that he had beaten her up, the former Another Level singer said: "No, of course not."
The court has been told that the incident in January happened after Ms Cahill quizzed him about why he had glitter on his face.
She became suspicious after spotting it as she tried to wake Mr Bowers. The couple had already split up but were living separately in the home they shared with Bowers' parents in Croydon, south London.
Ms Cahill said after she pointed out the glitter, he launched an attack in which he grabbed her by the shoulders, threw her out of a bedroom and hit her in the face, giving her a bloody nose, pulled her hair and squeezed her throat.
Mr Bowers, 35, who denies one count of assault by beating, said he had been to a circus-themed nightclub the previous evening because he was trying to help a friend get a job.
He says he got home at 02:00 or 03:00 GMT and spent time talking with his father.
The trial is ongoing.
Pop singer Dane Bowers has denied assaulting his ex-girlfriend, saying he was acting in self-defence when he hit her.