The former Disney Channel actress, 35, announced the news on Instagram, sharing two sweet snaps with her almost 13 million followers.
In the first picture, Tisdale and French, who tied the knot in 2014, stare down at her belly while she cradles her growing baby bump.
In the second photo, the couple smile while looking into each other’s eyes.
Tisdale’s celebrity friends congratulated the couple in the comments section.
Her High School Musical co-star Vanessa Hudgens wrote: “Just the freaking cutest.”
Glee actress Lea Michele said: “So happy for you babe! You’re going to be the best mama!”
Big Bang Theory star Kaley Cuoco commented: “Omg congratulations!!!”
And actress Emma Roberts, herself expecting her first child, shared three love heart-eyes emojis.
Tisdale starred as Sharpay Evans in the High School Musical films and also played Maddie Fitzpatrick in the Disney Channel series The Suite Life Of Zack & Cody.
