Her appointment follows last month's departure of Frances Sheen to Emap Australia.
Ahmad has been working on the launch of Happy as executive editor, alongside consultant editor Jane Proctor. Northern & Shell appointed Eilidh MacAskill as editor of the title in February.
Prior to working on Happy, Ahmad's CV includes stints at Bella and Marie Claire Health & Beauty as well as The Sun, where she was deputy women's editor.
Apart from Happy, her most recent experience was on Cosmopolitan, which she joined as assistant editor in 2001. She soon became deputy editor and spent two six-month periods as acting editor.
Julie Harris, general manager of Hachette's women's group, said: "Nina's extensive editorial background makes her perfectly placed to take B on to its next stage of development."
B's average circulation for July-December 2004 was 166,145, up 30% period-on-period. However, this represented a recovery after a previous circulation dive and the circulation is level compared with July-December 2003.
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