West Australian detectives have praised members of the public who were quick to act after hearing the screams of a woman in Perth who was physically and sexually assaulted on the weekend.

Kellerberrin man Dillon Smith, 27, appeared in Perth Magistrates Court on Sunday afternoon charged with several offences over the incident, including aggravated indecent assault, assault occasioning bodily harm and aggravated assault with intent to rob.

The woman in her 20s had finished work about 4.20am on Sunday and was walking to her car on Aberdeen Street when police allege Mr Smith approached her and asked for money.

A police spokeswoman said when the woman declined to give him money it is alleged he physically and sexually assaulted her.

Nearby residents and members of the public heard the woman's scream and came to her assistance.

According to detectives, without their intervention the woman could have been more seriously injured.

The woman received face, head and neck injuries and was taken to Royal Perth Hospital for treatment.

Mr Smith did not apply for bail and will next face court via video link on February 21.