Jones finished with nine points and 11 rebounds.
ETSU's A.J. Merriweather converted a three-point play with 49 seconds left in overtime to tie it at 71. After Eric Robertson missed a 3-pointer, Jones grabbed the offensive rebound with 21 seconds remaining, setting up his game-winner.
Robertson made 6 of 11 from 3-point range and scored 20 points - all career highs - for Chattanooga (11-7, 4-1 Southern Conference). Ronrico White added 16 points and seven assists and Martynas Bareika scored 13.
Jalen Riley led ETSU (9-5, 4-2) with 18 points.
Chattanooga made just 35.5 percent of its 62 field goal attempts, but hit 13 3's and 14 of 17 free throws. The Bucs, who shot 45 percent from the field, were 9 of 20 from the stripe.