Johnson was fouled while scoring on a layup with 1:30 to play and then knocked down a free throw to put Vanderbilt (24-10) ahead 65-62.
The play capped a 16-2 run late in the game that secured the unranked Commodores their first SEC tournament championship since 1951.
Top-ranked Kentucky (32-2) saw its bid for a 28th title foiled and its 24-game winning streak come to an end. The Wildcats remained a likely choice for a No. 1 seed in the NCAA tourney.
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