Lionel Patea will spend at least 20 years behind bars for the murder of a Kiwi woman, in a brutal Gold Coast slaying.

The 25-year-old unexpectedly pleaded guilty today in the Brisbane Supreme Court, on the first day of his trial.

Patea bludgeoned his 24-year-old former partner Tara Brown to death with a metal fire hydrant cover.

He'd chased her down and run her car off the road on a suburban Gold Coast street.

Patea stood in the dock with his cuffed hands clasped in front of him.

He did not show any emotion as the judge read through the ghastly details of the murder - which he claims he cannot remember committing.

Justice Debra Mullins then handed down his sentence.

"You are sentenced to life imprisonment. The conviction is also recorded as a conviction for a domestic violence offence."

Patea had written a letter to the court expressing remorse, but that had no bearing on the sentence.

Miss Brown's family has emerged from court and expressed relief the ordeal is over.

Her mother Natalie Hinton said she wants people to learn from her daughter's death - and speak up if they are experiencing domestic violence.

She said there is help out there.