Rapture, Blister, Burn, billed as a "witty dissection of gender politics", runs from 22 January to 22 February 2014 (previews from 16 January), directed by Peter DuBois.
After university Catherine and Gwen chose opposite paths: Catherine built a career as a rock-star academic, while Gwen built a home with a husband and children. Decades later each woman covets the other's life, and a dangerous game begins as each tries to claim the other's territory.
Gionfriddo's previous plays include Becky Shaw (Almeida Theatre) and After Ashley (Vineyard Theatre).
Next up is Good People by Pulitzer Prize winner David Lindsay-Abaire, running from 5 March to 5 April (previews from 27 February).
Set in south Boston, it will star Imelda Staunton as a sharp-tongued single-mother, Margie, who will do anything it takes to pay the bills after losing yet another job.
Jonathan Kent (Sweeney Todd, Private Lives), making his Hampstead Theatre debut, directs.
Having originally premiered on Broadway, Good People won the New York Drama Critics Circle Award for Best Play of the Year. Lindsay-Abaire won the Pulitzer for his critically acclaimed Rabbit Hole, which became a film starring Nicole Kidman.
"It is a real thrill to be able to introduce these two outstanding plays to British theatre-goers for the first time," said Hampstead artistic director Edward Hall.