Lauren Worsham and Julian Ovenden will also be featured in the Kern and Hammerstein musical.
Hill looks back on his time in the Duke Ellington-Cotton Club musical on Broadway.
Duke Ellington's musical legacy is on display at Broadway's Brooks Atkinson Theater.
The Broadway favorite joins an impressive list of performers who have taken on the show's "Special Guest Star" role.
Williams will join the cast this April.
Roundabout Theatre Company's revival of Sophie Treadwell's 1928 drama is directed by Lyndsey Turner.
Previously announced participants include Broadway veterans Sierra Boggess, Liz Callaway, and Beth Fowler.