Alison Sharland, who accepted £10m in her divorce, and Varsha Gohil, who got £270,000, say the men hid the extent of their wealth when the deals were made.
Both claims will now go back to the High Court.
The ruling could pave the way for many more people to seek to renegotiate their divorce settlements. BBC legal correspondent Clive Coleman said it was an "incredibly significant ruling" that meant a division of the parties' financial assets had to be based on a "valid agreement". "If one of the parties is dishonest, if they are misleading about what their assets are, then this is a very clear signal that the other party can go back to court, can have the agreement set aside and can have the whole thing considered again," he said.