Boulous converted from a corner kick in the 72nd minute and Pierre Louis finished after being denied on several chances - the first goals by either team in three games. Nadia Valentin added a final tally in the 83rd.
"I think the match shows where we are in CONCACAF and in the Caribbean," Haiti coach Ronald Luxieux said. "We were at our best and played our strongest. Now in the next years we will have to continue to work to reach the level of the best in CONCACAF."
Both teams entered the game already eliminated from Olympic contention, with Haiti having been outscored 8-0 in its previous group matches against Canada and Costa Rica, and Cuba shutout 4-0.
Haiti had the better of possession and chances, although the Cuba opened the second half with the best chance for either side until Boulos' and Pierre Louis goals.
Rachael Pelaez broke down the left side of the penalty area in the 47th minute, drove on the Haitian goal until she switched the ball to her right foot. As she approached the corner of the goal box, she shot only to have Haitian keeper Geralda Santilus knock it away with her extended left foot.
From then it was largely Haiti - which contolled the first half, with Valentin and Pierre Louis both testing Cuban keeper Lucylena Martinez.
Haiti finally went ahead on Pierre Louis' corner. Sophia Batard was able to head the ball down at the edge of the six, and Boulos was able to spin and drive the ball past Martinez from three meters.
Pierre Louis scored her own in the 76th, taking a feed on the right side from a falling Batard, driving into the area and shooting across Martinez inside the far post.
Valentin completed the scoring, running onto a ball from Wisline Dolce, shielding off her defender and finishing from 13 meters.
"At home we have nothing similar to a CONCACAF tournament," Luxieux said. "Most of the girls do play in Haiti and five play in other countries. To grow I think that many will have to attend schools in other countries to continue to develop and hopefully one day reach the level of Marta or Christine Sinclair."
Cuba, which arrived in Vancouver with only 18 of the allowed 20-player roster, played without two key regulars, who were listed as absent on the official lineup sheet. Both 22-year-old midfielder Yisel Rodriguez and 20-year-old forward Yezenia Gallardo started the earlier matches against Canada and Costa Rica.
They also played in all three qualifying matches, when Gallardo scored five of Cuba's 10 goals - including four in a 6-0 win over Aruba in June.