The actresses are expected to reprise their roles for the third installment in the wildly popular Disney franchise. It will be the first "HSM" flick to get a theatrical release, after two previous films were enormous hits on television.
A source told Us Hudgens will receive a "substantial increase" in pay.
Rumors have swirled for months that Hudgens might not be asked back for another "HSM" outing after nude photos of her surfaced on the Web. That seems to be behind her now, however.
"Vanessa is locked for the movie," a source told the magazine. "She is very happy that the deal is done."
A source close to Hudgens confirmed: "The contract will be signed within the next week. ... It is almost a done deal."
Someone from the Tisdale camp said of her negotiations, "It's done, done, done."
The movie is set to begin shooting in January.