The 60-year-old deceased was among the two injured who were rushed to the hospital.
A fire department spokesman Lars-Ake Stevelind said earlier: "An improvised explosive device may have been detonated". Two people, aged 45 and 60, have been rushed to the nearest hospital".
The local media quoted Stockholm's police force as saying that the man succumbed from his injuries while being rushed to the hospital.
"There was something on the ground that the man picked up, and then it exploded", Sven-Erik Olsson of the Stockholm police said.
The police force refuted claims that the man was unlikely to have been purposely targeted by whoever left the explosive at the metro station.
The Aftonbladet newspaper reported that the blast was from was a hand grenade, though this is yet to be confirmed by the police.
The metro station has been shut and nearby areas have been cordoned off from the public as an investigation is currently on.
It is yet to be ascertained whether it is a terrorist incident or not.
Stockholm is on high alert since the April 2017 attack in the heart of the city, when a truck was deliberately driven through the crowd, killing five people and injuring 14 in the process. (ANI)