A young pedestrian is fighting for life in hospital after he was hit by a car and left for dead on a suburban street, police allege.

Ty-Kai Yarran, 20, was with a friend outside his home on Steerforth Dr in Coodanup, an hour south of Perth, when he was struck just after 9.30pm on Monday.

WATCH THE VIDEO ABOVE: Pedestrian struck in alleged Coodanup hit-and-run.

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His family rushed outside, finding him lying unconscious on the road.

Yarran was rushed to Peel Health Campus with life-threatening injuries.

He was later transferred to Royal Perth Hospital, where he remains in a critical condition in intensive care.

His mother is by his side.

Yarran’s grandmother Melinda Miller described him as a “beautiful young man”.

“He means the world to me, my grandson,” she told 7NEWS.

Police say the driver failed to stop and fled without calling for help.

The moment of impact was captured on security video.

A 37-year-old man has been taken into custody and is assisting police, and a white Hyundai Getz has been seized.

No charges have been laid.

Anyone with information should contact Crime Stoppers.