The $60,000 renovation comes on the heels of several other projects the We're the Millers actress has completed on her home, E! Online reported.
According to documents filed with the Los Angeles Building and Safety Department, the new closet will also feature a powder room.
In December 2012, she began work on expanding the master bedroom, which she shares with fiancée Justin Theroux.
The house has also seen the addition of a deck with trellis, the removal of an existing trellis, and a new cantilever roof, library and dining room.
Aniston and Theroux moved into the pad just a few weeks go.