It is believed Andre Murphy, who was known as Nick, was hit while fixing a flat tyre on his horse trailer at about 04:10 GMT at junction 28 on Monday.
The stud farmer, 56, from County Wexford in Ireland, was on his way to deliver horses at the time.
A man, 45, arrested on suspicion of causing death by dangerous driving has been released on bail.
County Wexford parish priest Father James Nolan said Mr Murphy's death was a "tragedy for all involved".
"His heartbroken wife Julie is being comforted by family and friends," he said.
"He was well known and respected by all in the equestrian community. He will be missed," he added.
Gwent Police said a passenger, 29, who was travelling with Mr Murphy, was uninjured.
A man killed in a crash which led to 11-mile tailbacks on the M4 around Newport has been named.