Police have charged a 16-year-old boy over the violent sexual assault of a 23-year-old woman in South Fremantle at the weekend.

It is alleged the teenager entered the woman's house on Wesley Street in the early hours of Saturday morning, armed with a knife, and sexually assaulted her.

He has been charged with six offences including aggravated burglary, sexual penetration without consent, unlawful wounding and threatening to kill the woman.

The teen is due to appear in the Perth Children's Court tomorrow.