The 29-year-old explained his bizarre superstition in new autobiography My Story, which is being serialised in The Sun this week.
Vardy admitted that he enjoys around 250ml of port - the equivalent of three double shots - out of a Lucozade bottle the night before a game.
"I can't say why it started, because I genuinely don't know, but I decided to drink a glass of port on the eve of every game in the 2015–16 season," Vardy wrote. "I'm not normally superstitious but from the moment I scored against Sunderland on the opening day, I didn't want to change anything.
"I fill a small plastic water or Lucozade bottle to halfway and just sip the port while watching television. It tastes like Ribena to me, and it helps me switch off and get to sleep a bit easier the night before a game."
Vardy has previously revealed that on a matchday itself, his diet consists of three cans of Red Bull, a double espresso and a cheese-and-ham omelette with baked beans.