Adams scored 13 points with 10 rebounds, while Chievous had 12 and 10 for Hampton (8-7, 4-0 Mid-Eastern Athletic Conference). Brian Darden added 11 points.
Chievous made two free throws and then a jumper to put the Pirates up four just more than a minute into overtime. FAMU (5-12, 1-3) pulled within one with three minutes left, but missed its last six shots - all from 3-point range - while Adams and Darden each hit 3s for Hampton to close out the scoring.
Johnson made 1 of 2 free throws with 52 seconds left in regulation to tie it at 62 and, eventually, send it to overtime.
Malcolm Bernard led FAMU with 23 points and 11 rebounds.
The Rattlers shot just 28.6 percent (16 of 56), including 6 of 26 from 3-point range, and committed 18 turnovers.
The Pirates outrebounded FAMU 52-37, including 17-8 on the offensive glass.