A Perth martial artist who had killed his wife by a single punch in the head, then left her body to rot in a bedroom, has been sentenced by the WA Supreme Court today to five years in jail.

Bradley Wayne Jones, 34, will serve a minimum of three years for the manslaughter of Saori Jones, 31, in December last year.

Jones had pleaded guilty to the assault that happened in front of their children, aged four years and 10 months.

The martial artist was reportedly drunk when he learned that his then estranged wife was having an affair with the best man from their wedding. He had punched his wife in the head in front of their children, then he took her to a bedroom and put a blanket over her as she was bleeding and vomiting. Saori did not get first aid or any medical attention. Her husband found her dead the next day.

Police found the decomposing body following a search.

In sentencing, Supreme Court judge Lindy Jenkins said that allowing his wife's body to decompose for two weeks while Jones ignored it, "forcing the children to live with the body", was a "degrading action".

In giving the sentence, the judge accepted that alcohol had contributed to the offence.

Jones will be eligible for parole in December 2013.