The 36-year-old Serbian had been indestructible on Wimbledon's Centre Court for a decade but finally met his match as he ran out of ideas to stop young gun Alcaraz from hurtling towards the title in the grasscourt major.
After the 20-year-old had broken for a 2-1 lead in the fifth set with a stupendous passing shot winner, Djokovic's racket felt the full force of his anger as he smashed it against the wooden net post to leave it in a mangled mess.
That earned the Serbian a second warning in the match, with Djokovic having also been cautioned earlier for taking too much time to launch into his serves.
The distraction failed to throw Alcaraz off course as he became the youngest man since 18-year-old Boris Becker in 1986 to win the Challenge Cup after Djokovic scooped a forehand into the net, leaving the Spaniard to fall on his back in triumph.
"It's a dream come true for me. It's great to win ... making history in this beautiful tournament," world number one Alcaraz said as he cradled the trophy during the presentation ceremony.
To sum up what it meant to play a part in a match billed as the "collision of generations" Alcaraz then paid tribute to his victim, who had won the last four Wimbledon men's titles.
"I have to congratulate Novak. It's amazing to play against him. You inspire me. (When) I was born, you were winning tournaments."