NBC announced on Friday that Tate will return during the second half of the sitcom's current season when Nellie is hired as a special projects manager by Sabre's corporate office.
"Catherine is hysterical. We introduced her briefly in last season's finale and knew she had to be a part of the show somehow," explained executive producer and Office cast member Paul Lieberstein.
"We'll meet her again as corporate's special projects manager, and her relationship with Robert California (James Spader) will be far from professional. We're thrilled that she's joining the cast."
Tate first appeared in The Office's season seven finale as a candidate for the role vacated by departing cast member Steve Carell's on-screen character Michael Scott.
She was recently rumoured to be dating Take That musician Jason Orange.
Watch a promo for Catherine Tate's original appearance in The Office below: