"This morning, one of the BASF firefighters who was critically injured in the October 17 explosion ... succumbed to his wounds," BASF said in a statement.
An explosion followed by a fire rocked the chemical giant's plant in Ludwigshafen, where 36,000 people work.
Another seven people were critically injured and 22 others slightly wounded.
BASF employs over 100,000 people around the world and had sales of more than 70 billion euros ($76.77 billion) in 2015.
The firm's worst accidents lie many decades in the past, including a 1921 explosion in a Ludwigshafen ammonia factory that killed 585 people and a 1948 accident on the same site in which 207 were killed and 3,800 injured.