Jon joined the Cleveland Museum of Art in 2007 and in 2008 reinstalled the permanent collection of European painting and sculpture in phase I of the museum’s renovation and expansion project. He spearheaded a number of acquisitions, including important works by Pedro de Mena, Alessandro Cesati, and Mino da Fiesole, and he is currently planning several exhibitions, including The Last Days of Pompeii: Decadence, Apocalypse, Resurrection, opening in 2013. Seydl also curated the Cleveland presentation of the recent exhibition Rembrandt in America and completed the installation of the Renaissance collections in 2012

Seydl began his career in 1991 as a program specialist in the National Endowment for the Humanities Museums Program. In 1994, he joined the Philadelphia Museum of Art as a research coordinator for the international exhibition The Splendor of Eighteenth-Century Rome, which was presented at the Philadelphia Museum of Art and the Museum of Fine Arts, Houston, in 2000. In 2002, he joined the J. Paul Getty Museum as assistant curator of paintings and was named associate curator of paintings in 2006. During his tenure in Los Angeles, Seydl coordinated the presentation of Jacques-Louis David: Empire to Exile (2005) at the Getty and curated Tiepolo Oil Sketches (2005), for which he also wrote the catalogue. He also co-curated the exhibition From Caspar David Friedrich to Gerhard Richter: German Paintings from Dresden (2006–2007), and co-edited two books of essays, Antiquity Recovered: The Legacy of Pompeii and Herculaneum (2007), and Gerhard Richter: Early Work, 1951-72 (2010).

He received a BA in art history from Yale University in 1990, and earned his MA (1998) and PhD (2003) in art history from the University of Pennsylvania, specializing in Italian art of the 17^th and 18^th centuries and writing his dissertation on images of the Sacred Heart of Jesus in the 18th century.