Halnaker is a hamlet in the Chichester district of West Sussex, England. It lies on the A285 road 3.5 miles (5.6 km) northeast of Chichester, where it follows the line of the Roman road to London called Stane Street. There is a pub, The Anglesey Arms. Goodwood House is southwest of the village. North of the village Halnaker Windmill stands on 128 metre/420 feet high Halnaker Hill, a southern outpost of the South Downs. It is in the civil parish of Boxgrove.