Before joining the Dallas Museum of Art, Walker was director of the National Museum of African Art, Smithsonian Institution, from 1997 until 2002. She had served in curatorial positions at that institution since 1981. Prior to that, Walker was director of the University Museums at Illinois State University, Normal, and was curator of its ethnographic art collection from 1975 to 1981. She's also held curatorial positions for the Institute of African Studies at the University of Ibadan in Nigeria, the Federal Department of Antiquities, National Museum, in Lagos, Nigeria, the University Art Gallery at the University of Massachusetts Amherst, and the Museum of African Art in Washington, D.C.
During her tenure at the Dallas Museum of Art, Walker has curated several exhibitions, reinstalled the Arts of Africa Gallery, and published The Arts of Africa at the Dallas Museum of Art in 2009. She edited and contributed an essay to The Power of Gold: Asante Royal Regalia from Ghana, which accompanies the exhibition.