This office belonged to Dolores Umbridge as she was Senior Undersecretary to the Minister. She decorated it as she had decorated her office at Hogwarts. It had lace drapes, doilies, and dried flowers covering every available surface. On the walls, there were plates which had a uniquely painted cats on each one. There was also a highly polished desk which had a flowery cloth covering it. In the desk there were quills, ink and Spellotape; enchanted paperclips that coiled snake-like around the drawer; a fussy little laced box containing spare bows and clips; also a little box containing pink paper with small cats at the bottom.
During the puppet administration of Pius Thicknesse, this office also served Dolores Umbridge in her capacity as Head of the Muggle-Born Registration Commission. In this capacity, the office contained a filing cabinet behind the desk that Harry compared it to the one in Filch's office. It contained various files with the names of various workers at the Ministry. During this time, the office also contained a telescope attached to Alastor Moody's magical eye which Umbridge used to spy on the workforce in the outer office.
It is unknown what use this office came to after Umbridge was removed from power, likely the next Senior Undersecretary to the Minister, occupied it.