Police received a report of a road traffic collision on the M4, near Newport, at around 9pm on Monday 29 January.
Officers remain at the scene after the collision involved three cars – a BMW X4, a Vauxhall Agila and a Volkswagen Polo – between junctions 28 and 29 heading east.
The driver of the Vauxhall, a 52-year-old Newport man, was pronounced dead at the scene and his next of kin have been informed and are receiving support from specialist officers.
A Cardiff man, 34, was arrested on suspicion of causing death by dangerous driving and remains in police custody as enquiries continue.
Superintendent Mike Richards said:
“While our officers continue to work at the scene of the collision, all lanes of the motorway between junctions 28 and 30 on the eastbound side are currently closed and diversions are currently in place with this incident still ongoing.
“We know that there is likely to be a high level of travel disruption so we’re asking motorists to avoid the area and follow the diversions which are in place.”