Cardiff complete signing of striker Cornelius
Cardiff said the 20-year-old, their first recruit ahead of City's Premier League debut in August, had a medical on Monday and would join his new team mates next week after a short vacation.
No transfer fee was given but media reports said it was around eight million pounds.
"The Danish national team always wants players playing in foreign countries, especially in the English Premier League," Cornelius told the club website.
"If I can improve as a player at Cardiff City, which I think I can, then I can be a better player for the Danish national squad as well."
Cornelius was the top scorer in the Danish Superliga last season, scoring 18 goals in 32 appearances in his first full campaign in the top flight. He also graduated from university last weekend.