The casting will reunite the Broadway favorite with "Gilmore Girls" creator Amy Sherman-Palladino, who cast the singing actress in Foster's first TV series, "Bunheads," and stage and screen star Kelly Bishop, who appeared in both series.
Foster's role has yet to be announced. She will join returning "Gilmore Girls" actors Lauren Graham, Alexis Bledel, Kelly Bishop, Scott Patterson, Milo Ventimiglia, Matt Czuchry, Liza Weil and Yanic Truesdale.
A premiere date for the Netflix series has also yet to be announced.
Foster, who can currently be seen on TV Land's "Younger," won her Tony Awards for her performances in Thoroughly Modern Millie and Anything Goes.