After heartbreak in Beijing, London, Rio de Janeiro and Tokyo, Djokovic simply would not be denied the one title that had eluded him for so long, winning 7-6(3) 7-6(2) in front of a enthralled crowd on Court Philippe Chatrier.
Top seed Djokovic delivered one of the finest performances of his career to deny Alcaraz and become only the fifth player to win all four singles Grand Slams and the Olympic title.
Neither player took a backward step in a ferocious contest in which the first set alone lasted one hour 33 minutes as they wrestled for control in a series of spellbinding games.
Alcaraz cracked first in the tiebreak and when another tiebreak was required to decide the second set, again Djokovic again found another gear, sealing victory with a stunning forehand winner down the line.
Djokovic roared to the sky and after shaking hands with Alcaraz he fell to his knees on the centre of the court before climbing into the crowd to be swamped by his family and team.
Alcaraz, who was denied the Olympic title to go with this year's French Open and Wimbledon crowns, was in tears at the end.
