LaFond soared 15.01 metres on her second attempt, the best jump in the world this year, and with victory all but locked up was able to pass on her remaining four jumps.
"This feels absolutely surreal," LaFond said.
"I'm the only athlete here from my country and I have the gold medal. We're just a little island with a population of 70,000 people, so this one is for my people, all of my people."
Cuba's Leyanis Perez Hernandez leapt 14.90 for silver, while Ana Peleteiro-Compaore of Spain won bronze with a mark of 14.75.
LaFond's previous best results were a Diamond League win in 2022 in Paris and Commonwealth Games silver and bronze medals.
"My country is small but mighty. I came here with the expectation and the goal of jumping 15 metres," she said.
"I am hoping that this inspires the next generation of young Dominica athletes to just go for it.
"I am hoping that for some kid watching this on their phone, on the TV, or on the live stream, this lights a little flame in their heart that can drive them to something amazing."
Hamish Kerr of New Zealand cleared a world-leading 2.36 metres to win the men's high jump gold, improving on his bronze from the 2022 world indoor event.
American Shelby McEwan won the silver with a jump of 2.28, and reigning indoor champion Woo Sang-Hyeok of South Korea was third, also clearing 2.28 but with more foul jumps.
