A Perth teenager who stabbed and killed his abusive stepfather in order to "protect" his eight-year-old sister has avoided jail.

The teenager appeared in the Supreme Court of WA for sentencing on Wednesday, and the court again heard details of the violent abuse the teenager, his disabled brother, sister and mother had suffered at the hands of his stepfather.

The teenager was due to be sentenced last Thursday but his case was adjourned. Credit:Heather McNeill

The 18-year-old, who cannot be named for legal reasons, was 17 when he killed his 36-year-old stepfather inside their Girrawheen home two years ago.

On the night of September 16 2016, the court heard the heavy-drinking stepfather had consumed eight or nine beers when he choked the boy's 15-year-old brother.