The winger has been one of the stars of the show for the Foxes this season as they eye an instant return to the Premier League.
And Leicester went in front after just ten minutes of their Monday night clash at St. Andrew's with Mavididi rounding off the move.
Abdul Fatawu played him through just seconds after a Blues corner and the latter delightfully chipped over John Ruddy.
Mavididi ran straight towards the advertising boards in front of him, climbed over them and sat in front of the home fans in celebration.
Birmingham supporters were visibly angered, with Leicester midfielder Harry Winks holding his hands up in an apparent apology gesture.
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The hosts hit back just minutes later though when Jordan James found the bottom corner with his strike.
However, Leicester restored their lead in the 21st minute, with Kiernan Dewsbury-Hall the scorer this time after taking the ball round Ruddy and firing into an empty net.
He too was more than happy to celebrate in front of the Birmingham fans in what was an exciting first-half.
However, he didn't take the step of going over the advertising boards to taunt them like Mavididi, who scored his second and Leicester's third of the night early in the second-half.
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James scored again for Birmingham but it wasn't enough as they fell to a 3-2 defeat, with the bottom half Blues still struggling under Wayne Rooney having been sixth when John Eustace was in charge.
Leicester's win keeps them top of the Championship and three points clear of Ipswich in 2nd.