First based at Al Jazeera English's main US bureau in Washington, D.C. and then in Al Jazeera America's San Francisco Fault Lines show hub, he was a presenter on Fault Lines, the channel's flagship news magazine about the Americas, and reported from across the continent.

[1] Before joining Fault Lines, Walker was a foreign correspondent with a particular interest in Haiti.

[4] Walker won a DuPont-Columbia University Award in Broadcast Journalism for his work in Haiti.

[7] Walker has also repeatedly covered the Occupy movement in the US and the shooting of Michael Brown near St. Louis, Missouri, which precipitated sustained protests.

[citation needed] Walker has worked for the Baghdad Bulletin,[8] and various international news organisations, including Reuters[9] and AFP, and has reported from a number of key countries around the Middle East region, including: Iraq,[10][11] Libya, and Afghanistan.