Grint, who starred in all eight Harry Potter movies from 2001 to 2011, will join the play at the Lyric Theatre from February 2 to May 30, 2027.
"Ron Weasley has been a part of me since I was 11 years old and I can't wait to meet him again in this stage of life," Grint said in a statement.
"There is something so full-circle and so special about stepping back into Ron's shoes now when we are both fathers; it is somehow both very familiar and completely new."
It will mark the second time a member of the Harry Potter film cast has joined the stage production.
This year, Tom Felton reprised his role of Draco Malfoy, which was met with a jump in box office receipts.
The play picks up 19 years after the end of the final novel Harry Potter and the Deathly Hallows.
An adult Potter is married to Ginny Weasley, sister of his best friend Ron, who married brainy Hermione.
Both couples have children and all are in danger again.
Ron runs his own joke shop, Weasley's Wizard Wheezes.
"His return creates a powerful bridge between the story audiences first fell in love with and the story of family, legacy and the passage of time that Harry Potter and the Cursed Child carries forward," producers Sonia Friedman and Colin Callender said in a statement.
Grint made his Broadway debut in the original production of It's Only a Play, opposite Matthew Broderick and Nathan Lane.Â
He made his West End debut in Jez Butterworth's play Mojo, starring opposite Ben Whishaw.
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