The Victoria native scored a personal best 367.35 points to finish ahead of Montreal's Eloise Belanger and Calgary's Caeli McKay.
"I've had trouble with injuries and deciding whether I would continue in the sport so I was glad to see it all come together today," said Toth, who is coming back from an elbow injury. "I knew if I could do my dives like in practice I could surpass my goal of scoring 315 points."
Both McKay and Belanger finished the weekend by reaching the podium on all three boards.
Ottawa's Jamie Bissett repeated as national champion with a win in the men's three metre. He scored 437.10 points to finish ahead of Francois Imbeau-Dulac of St-Lazare, Que., and Montreal's Philippe Gagne.
"The key for me is the fifth dive and I did it well today," said Bissett, the winter nationals champion in January. "I was able to compete a couple of times internationally this spring and I really learned a lot."