Andrew Ryan had 12 points, Darius Leonard 10 and Marvelle Harris nine for the Camels, who won despite getting zero points from their bench.
Joab Jerome led Winthrop (7-10, 1-4) with 16 points, but the Eagles shot just 34.6 percent (9 of 26) in the first half as Campbell (9-10, 4-1) took a 34-24 lead into intermission.
Winthrop cut the deficit to two points three times before taking its first lead of the second half, 53-52, with 5:25 remaining behind a Derrick Henry 3-pointer. Henry made a jumper to put the Eagles up 55-52, but Campbell scored six straight to retake the lead, 58-55.
Jerome sandwiched two baskets around a Freeman jumper make the score 60-59, but Winthrop missed its final two shot attempts.