Liedtke was born in Plainfield, New Jersey, and grew up in Livingston, New Jersey. Liedtke studied Art History, receiving a Bachelor of Arts degree in 1967 from Rutgers University in New Brunswick, New Jersey, a Master of Arts degree in 1969 at Brown University in Providence, Rhode Island. He received a Doctorate at the Courtauld Institute of Art in London. Liedtke said that his interest in Dutch paintings began because he was focused on images as a child from hours and hours of watching a lot of TV. He described his aesthetic as that of having a focus on how he responded to visual patterns compared to a more typical perspective focused on story and narratives.
After receiving a Mellon Fellowship he began studying at The Metropolitan Museum of Art, where he was appointed in 1980 as curator and would spend the rest of his career. He organized numerous exhibitions, wrote seven books, including several on Rembrandt and Vermeer, and produced catalogues of the Museum's Dutch and Flemish paintings.
Liedtke served as a curator of European Paintings at the Metropolitan Museum of Art for thirty-five years. Liedtke specialized in the paintings of Vermeer and the Delft School. The 2001 Liedtke-curated show, "Vermeer and the Delft School" was said to be the most popular art exhibition that year, attracting 555,000 visitors during its three-month run.
At the time of his death he was preparing a catalogue of the museum's collection of Spanish paintings of the 15th to 18th century.
Most recently, he worked on "El Greco in New York," a collaborative project that was co-curated with Keith Christiansen, with the Hispanic Society of America and the Frick Collection held at the Metropolitan Museum of Art from November 4, 2014 to February 1, 2015.
Liedtke was married to Nancy Liedtke a math teacher, artist, and equestrienne. He commuted daily from the Metropolitan Museum of Art on the Upper East Side neighborhood of New York City to what he called "the countryside," Bedford Hills, New York in Westchester County. He said that he thought there was something "Dutch" about the way he lived: the idyllic countryside, his 100-year-old home, and his art collection, which he said was quintessentially Dutch in character.
Along with five others, Liedtke died in the February 3, 2015 Metro-Northcrash, at the age of 69.Thomas Campbell, director of the Metropolitan Museum of Art, described him as "one of the most distinguished scholars of Dutch and Flemish painting in the world." Many in the art and museum community posted reflections and appreciation of Liedtke's work. Memorial statements were widespread, and were both local and international in scope.
Liedtke, Walter A. Jr. Architectural Paintings in Delft: 1650–1675. A Thesis (PhD) – University of London (Courtauld Institute of Art), 1974. OCLC272495491
Liedtke, Walter A. Architectural Painting in Delft: Gerard Houckgeest, Hendrick Van Vliet, Emanuel De Witte. Doornspijk, the Netherlands: Davaco, 1982. ISBN978-9-070-28811-2OCLC9554399
Liedtke, Walter A., and Anthonis van Dyck. Antony Van Dyck. New York: Metropolitan Museum of Art, 1985. OCLC475286414
Bauman, Guy C., and Walter A. Liedtke. Flemish Paintings in America: A Survey of Early Netherlandish and Flemish Paintings in the Public Collections of North America. Antwerp: Fonds Mercator, 1992. ISBN978-9-061-53231-6OCLC489445924
Metropolitan Museum of Art (New York, N.Y.), and Walter A. Liedtke. Flemish Paintings in the Metropolitan Museum of Art. New York: The Museum, 1984. Published in association with the J. Paul Getty Trust. ISBN978-0-870-99356-5OCLC9785292
Liedtke, Walter A. The Royal Horse and Rider: Painting, Sculpture, and Horsemanship 1500–1800. New York: Abaris Books, a Woodner Foundation Company, in association with The Metropolitan Museum of Art, 1989. ISBN978-0-898-35267-2OCLC507217109
Brejon de Lavergnée, Arnauld, Barbara Brejon de Lavergnée, Katharine B. Baetjer, James David Draper, William M. Griswold, Walter A. Liedtke, Anne Norton, and Annie Scottez-De Wambrechies. Masterworks from the Musée Des Beaux-Arts, Lille. New York: Harry N. Abrams, 1992. ISBN978-0-810-96417-4OCLC901055202
Liedtke, Walter, Pieter de Hooch, Carel Fabritius, Johannes Vermeer, and Gerard Houckgeest. A View of Delft: Vermeer and His Contemporaries. Zwolle: Waanders, 2000. ISBN978-9-040-09490-3OCLC185854242
Liedtke, Walter. 2000. "The Study of Dutch Art in America". Artibus Et Historiae / Istituto Internationale Per Le Ricerche Di Storia Dell'Arte (IRSA). 2, no. 41, 2000. pp. 207–220. ISSN0391-9064OCLC886789750