An Amazon delivery driver was reportedly held at knifepoint before his attacker made off with his van and all the parcels inside.
The armed robbery, which happened on Sunday morning, took place in Burnham Avenue, Llanrumney.
The driver's van, which was full of parcels being delivered in the last two weeks before Christmas, was stolen just before midday.
Some of the packages were found later having been dumped in a nearby lane after the men made off with the delivery vehicle.
Two men, aged 23 and 31, have been arrested in connection with the incident, one of whom remains in police custody.
A spokesman for South Wales Police said: "Two men have been arrested in connection with a knife point robbery of an Amazon.com delivery driver in Cardiff.
"A 31-year-old man from Llanrumney has been arrested on suspicion of robbery and remains in police custody. A 23-year-old man from Llanrumney, also arrested in connection with the incident, has been released under investigation.
"Detectives are continuing to investigate the circumstances of the incident in Burnham Avenue, Llanrumney, just before midday on Sunday, December 6.
"The driver’s van was stolen along with around 30 parcels, some of which were later found discarded in a nearby lane."
