He defeated Sergey Karjakin in a series of tie-breaking games.
After twelve classical games of chess between Norwegian champion Carlsen and Karjakin, the Russian challenger, the two remained even, even after three weeks of play.
This forced the ultimate tiebreak series of four rapid matches in which each player was given 25 minutes to make moves.
Carlsen, who celebrates his birthday the same day, is known as a strong player in rapid-style chess games.
Norwegian Magnus Carlsen wins World Chess Championship for third time in a row https://t.co/MjRLNhFmre— AFP news agency (@AFP) 1 dicembre 2016
He proved it by defeating the more defensive-minded Karjakin in three of the four games to clinch the overall win.
The two competitors split the 1.1 million US dollar (one million euro) prize money.
Carlsen took home 660,000 USD (621,000 euro) for the win.
The game has been followed by an estimated six million players around the world. (Euronews)