A Melbourne man has pleaded guilty to killing his wife whose body was later found buried beneath their backyard deck.

Nasir Ahmadi, 47, had been committed to stand trial over the murder of Zahara Rahimzadegan after originally pleading not guilty to her December 2011 death.

He cried in the dock of the Victorian Supreme Court on Friday as he pleaded guilty to manslaughter.

"I'm guilty," he told Justice Elizabeth Curtain, shaking his head.

Ahmadi's 2012 committal hearing was told he had admitted to killing his wife to police.

He confessed to placing a cord around her neck and strangling her before burying her body under a recently-built deck.

It was alleged he was motivated by the belief his wife was having an affair.

Ahmadi will appear for a plea hearing on May 30.