Newcastle opened the scoring on three minutes after Peter Lovenkrands cross from the left-hand side of the box looped over Preston keeper Andy Lonergan and into the top corner.
North End nearly levelled on 16 minutes when Jon Parkin hit a rasping strike from close range that Steve Harper fended away.
In the dying seconds of the half Parkin’s volley flew inches wide, while United’s Andy Carroll forced Lonergan into a save early in the second half after a turn and shot.
Newcastle extended their lead just before the hour when Kevin Nolan exchanged passes in the box with Alan Smith and side-footed past Lonergan.
In stoppage time Ryan Taylor lashed home from six yards following Fabrice Pancrate’s cross.