Over the last 40 years, Widerberg has held more than 100 solo exhibitions, participated in nearly 130 collective exhibitions, and completed over 90 decoration assignments, both nationally and internationally. Among his most prominent works are the monuments of Thor Heyerdahl and Trygve Lie, and decorations at the Government Building, Gardermoen main airport, and Northumbria University in Newcastle. He is also known for creating the memorial monuments in 53 municipalities that lost residents in the aftermath of the July 22 tragedy. Through these exhibitions and public decorations, he has reached a large audience and is today considered one of the most significant sculptors of our time. He primarily works with sculptures in stone and bronze, but also with glass, through a collaboration with Hadeland Glassverk. In addition to being a sculptor, he has consistently worked with graphic art and painting. Widerberg is represented in several national and international art collections. These include the National Museum, Lillehammer Art Museum, Kistefos Museum, Nordea Art Collection, Statoil's Art Collection, Norges Bank, The Well, Parabola Estate, Newcastle, and The Johnson Collection, USA.