King, a transfer from Alabama, was a top 50 prospect coming out of Memphis East High School. He also played for Memphis for two seasons.
Brandon Walters and Giddy Potts both added 16 points for MTSU (6-1), whose only loss was to Belmont.
MTSU improved to 6-0 against the SEC and Big 10 since 2015.
Matthew Fisher-Davis came off the bench to score 17 points, including five 3-pointers, for Vanderbilt (3-6).
Jeff Roberson added 13 points for the Commodores, who have lost five of their last six games.
Vanderbilt's Riley LaChance missed a 3-pointer with two seconds left that could have tied the game. LaChance was 0-for-6 from distance.
The Commodores outscored the Blue Raiders 32-4 in bench points.
Vanderbilt took a 32-28 halftime lead as its bench outscored MTSU 17-2.
Vanderbilt has the worst record in the Southeastern Conference, but three of its losses were to ranked teams.
The Commodores entered the game last in the SEC in scoring (69.4 ppg) and field goal percentage (40.6).
Middle Tennessee: The Blue Raiders, who had a stunning win over Michigan State in the first round of the NCAA Tournament two seasons ago, continue to show they belong with Power Five opponents.
Vanderbilt: The Commodores lost another close game as they couldn't make the big plays in the closing minutes.
Middle Tennessee hosts Ole Miss (4-3) on Saturday before visiting another SEC team, Auburn, on Dec. 16. Ole Miss has lost two straight overtime games.
Vanderbilt visits 16th-ranked Arizona State (7-0) on Dec. 17 after an 11-day break for final exams. ASU's explosive offense ranks fifth nationally (92.7 ppg).
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