Courtney Duncan has won a fourth women's motocross world championship series crown after a successful final round in Turkey.

Kawasaki rider Duncan dominated the opening race in Afyonkarahiser to move 21 points clear of nearest rival Daniela Guillen of Spain.

27-year-old Duncan then finished second in the second race to clinch the title.

The former Palmerston rider adds the title to those she won in 2019, 2020 and 2021.

Consistent Dunedin rider Duncan didn't finish lower than fourth this season.

Hopes of a fourth successive last year were dashed when she suffered a broken collarbone in practice for the GP of Portugal.

"It's a long time coming, there's a lot of work that goes into it, so you just want to get there and get the job done," Duncan said in the leadup to the Turkey round.

"If you think about it, I've been working since Turkey last year for this one moment that's about to happen.

"I'm super excited and obviously a little bit anxious too, because you know how much it means, you know what's on the line."