The 22-year-old Angola international has agreed a five-year deal with the Championship club.
Vetokele, who represented Belgium at youth level, moved to Denmark in 2012 after spells with Belgian sides Gent and Cercle Brugge.
He scored 13 goals in 29 appearances in the Danish Superliga last season and featured twice in the Champions League.
Vetokele, who has won two caps for Angola, becomes Charlton's second signing of the summer.
Recently appointed Addicks head coach Bob Peeters brought in midfielder Yoni Buyens on loan from Standard Liege at the weekend.

Owners Hanwha Chemical Corp said the blast happened during welding work to expand a waste water disposal facility.
"Gas from the waste water, which had piled up inside the tank, was apparently ignited by the welding torch", a fire official told AFP.
An investigation into whether negligence was the cause of the explosion is under way.
The plant makes polyvinyl chloride used in wide range of products, such as cling film.

Wayan Sudarsa's body was found on Bali's Kuta beach on 17 August with head and neck wounds.
Sara Connor, 46, and her British boyfriend David James Taylor, 33, are both on trial for Mr Sudarsa's murder.
In court on Tuesday, his widow Ketut Arsini said she would not accept "even a cent" from Ms Connor.
The Australian woman read extracts to the Denpasar hearing of a handwritten letter she had sent to Ms Arsini offering 25m rupiah (Â£1500; $1900).
"I am not a rich person but to express my sympathy and my sadness I would like you to accept a donation of 25 million rupiah to help you and your children in this difficult moment," Ms Connor said.
People in the courtroom applauded when Ms Arsini said she did not want any money.
"I want the court to give the maximum punishment that fits what she did, based on Indonesian laws," Ms Arsini said.
Ms Connor again claimed her innocence, saying she tried to separate Mr Taylor and Mr Sudarsa after they began fighting over her missing handbag.
She told Ms Arsini she felt "great pain" over the tragedy.
"I'm deeply sorry for you and your family now left alone without Mr Sudarsa to care for you and your children. You have been always in my prayers," Ms Connor said.
Both Ms Connor and Mr Taylor face up to 15 years in jail if they are found guilty of murder.
The British man is scheduled to appear in court on Thursday.
Bali is a popular destination for Western tourists, known for its tropical climate and palm-fringed beaches. Petty crime is common on the resort island, though more serious crime is rare.
Charlton Athletic have completed the signing of FC Copenhagen striker Igor Vetokele for an undisclosed fee.
[NEXT_CONCEPT]
At least four people have been killed in South Korea in an explosion at a chemical plant in the city of Ulsan.
[NEXT_CONCEPT]
The widow of a policeman allegedly murdered in Indonesia has rejected a "donation" from his accused Australian killer.