New Jersey made up a 12-point deficit in the fourth quarter to force the extra period. Travis Outlaw hit two free throws with 10 seconds left in regulation to bring the Nets into a 79-79 tie.
The Bobcats then dominated the final minute of overtime after Wallace made his layup with 1:19 to go. Stephen Jackson made four key free throws during the late surge.
Jackson, returning from a one-game suspension, scored 25 points with six assists and five rebounds.
New Jersey shot just 31.9 percent from the field and made only 2-of-12 in overtime. The Nets were paced by 21 points from Outlaw and 19 by Anthony Morrow.