The loss eliminated the French Caribbean island, playing in the CONCACAF finals for only the second time and first since 1992.
Canada, which beat Guadeloupe 2-1 in the tournament opener on Monday, will play Costa Rica in the Group C finale on Friday with the Central American side needing only a draw to claim a seeded place in the final eight.
Quarterfinal winners will qualify for the U-20 World Cup.
Campbell threatened within the first three minutes and Costa Rica dominated possession and chances throughout. Guadeloupe struggled to mount any sustained offensive forays and didn't have a shot on goal past the 12th minute.
Guadeloupe keeper Kevin Anselme turned away several first-half chances to frustrate Costa Rica, including blocking shots by Campbell in the 16th and 19th minutes and another 27th that was ruled offside.
Campbell finally scored in the 57th, running onto a ball down the right side from Yelstin Tejada, turning inside defender Jeremie Valmy and curling in a left-footed effort off the far post.
Costa Rica doubled its lead in the 63rd when Campbell converted a penalty, earned when Anselme took out the legs of Deyver Vega at the right post.
Vega scored one of his own 11 minutes later, trading passes with second-half substitute Joshua Diaz Azofeifa at the top of the penalty area and breaking through on the left side to score from the edge of the six.
Guadeloupe finished with nine men after Lewis Laporal drew two yellow cards in 13 minutes and was ejected in the 79th minute, and Valmy was sent off in injury time for a last-man foul in the penalty area on Joseph Mora.
Costa Rica also finished short-handed, playing the final six minutes with 10 men after Mynor Escoe Miller was carted off with an apparent knee injury after the Ticos already had used their three substitutions.
Costa Rica had a chance to add a final goal in injury time on a penalty awarded for Valmy's foul, but Vega pushed his shot wide of the left post.