Ahmed began her career as a BBC graduate news trainee in 1990. In 1996 she became the broadcaster's Los Angeles correspondent and covered the OJ Simpson trial.
She went on to join ITN, which produces Channel 4 News, in 2000 as a reporter before becoming a presenter in 2002.
Then in 2004, she worked on the Channel 4 documentary series Islam Unveiled, exploring the status of Muslim women around the world.
Ahmed said today that she intends to go freelance, but wrote on Twitter that she would be doing some work as a presenter on BBC Radio 4, adding: "the BBC mothership is beckoning me".
Channel 4 News recently announced a number of changes to its presenting team, with political correspondent Cathy Newman named as a new regular presenter.
A number of high-profile BBC staff have joined Channel 4 recently. It was announced earlier this month that Paul Brannan, the BBC's editor of emerging platforms, will head up Channel 4's online team as senior programme editor.
Alongside Brannan's departure, BBC World News America anchor Matt Frei left to become Channel 4's Washington correspondent and Newsnight correspondent Jackie Long has moved over to become social affairs editor.