Watson's apartment is her second apartment which she leased after Sherlock Holmes left NYC for London in 2015. It's located in Chelsea and the apartment number is 6A. It has one bedroom and the large living space is used as a kitchen, living room and home office. Its first appearance is in the Season Three episode "Enough Nemesis To Go Around".
Watson's apartment is first seen as she delivers the results of a case to a client whose brother was skimming money from a home renovation business. Watson feeds Clyde whose terrarium is located between the bedroom and bathroom. She meets a neighbor Andrew who becomes her boyfriend. ("Enough Nemesis To Go Around") Watson is seen through one of the apartment windows reading the file Sherlock gave her on Kitty. ("The Five Orange Pipz") Kitty visits the apartment to report on a client she was surveilling for Watson. They then discuss Kitty's background. Later, Sherlock calls and wakes Watson as she's in bed with Andrew. Sherlock visits and meets Andrew coming out of the bathroom. After Andrew leaves, he and Watson discuss Kitty's need for a support group. ("Just a Regular Irregular")
Andrew discusses his involvement with Sherlock on an case pertaining to artificial intelligence with Watson. Later, Andrew has champagne ready in the kitchen and tells Joan that he met his future business partner while working on the case and will be leaving for Copenhagen. ("Bella") Kitty talks to Joan about taking care of Clyde while Watson was in Copenhagen with Andrew. She mentions making friends with a group at a coffee house near The Brownstone. ("Terra Pericolosa") Watson meets with Kim Holder about her missing sister, Jessica. Later, Watson makes a welcome home dinner for Andrew who is returning from Copenhagen. ("The Adventure of the Nutmeg Concoction")
