Two lanes and the junction 28 A48 slip road were closed following the collision at about 04:15 GMT on Monday. They have since reopened.
A 56-year-old man died at the scene. His passenger, 29, was not injured.
A 45-year-old from Merthyr Tydfil was arrested on suspicion of causing death by dangerous driving.
Both the driver and passenger were from Ireland.
Tailbacks were reported to junction 33 on the M4 and to the A4232 (Pontprennau) on Eastern Avenue.
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A man has been arrested following a crash on the M4 which left one person dead and 11 mile (18km) tailbacks from Newport to Cardiff.