The stage legend will play a mysterious character of great importance in Vanessas (Eva Green) past.
In addition, award-winning British actors Helen McCrory and Simon Russell Beale have been upped to series regulars.
McCrory returns as Evelyn Poole (a.k.a. Madame Kali), the seductive spiritualist who will pose a unique threat to our protagonists this season, along with Beale, who is back as eccentric Egyptologist Ferdinand Lyle.
Production on the second seasons 10 episodes, written by John Logan, will begin in September in Dublin, Ireland for a 2015 debut on the network.
Cast members McCrory and Beale will be joined by a wealth of new guest stars this season.
In addition to LuPone, Tony Award winner Douglas Hodge signs on as Bartholomew Rusk, an intense Scotland Yard investigator on the hunt to discover who is responsible for the terrible murders that have been plaguing London.
Sarah Greene will play Hecate, Pooles powerful daughter and Jonny Beauchamp will portray a young man with a singular past.
They will join series regulars Evan Green, Josh Hartnett, Timothy Dalton and Harry Treadaway.
(Photo Credit: Ethan Hill)