The trio will appear with the previously-announced Megan Hilty in a version of Smash's Marilyn Monroe biographical musical 'Bombshell', according to Broadway.Com.
All 22 songs written by Tony and Grammy award-winning pair Marc Shaiman and Scott Wittman will be performed to benefit the Actors Fund on June 8, one day after the Tony Awards.
McPhee confirmed the reunion. "It's so cool. I'm going to be there - me and Megan - everyone - Debra, Anjelica.
"It's going to be so fun. That was such a great, really fun - another really special job."
'Smash' was cancelled in May 2013 at the end of its second season.
McPhee has gone on to star in CBS procedural drama 'Scorpion', which was renewed earlier this week.