He graduated from the State Higher School of Plastic Arts in Łódź (1974-75) and the Institute of Art Education at Maria Curie-Skłodowska University in Lublin (1975-79, diploma from Jan Popek's workshop). In 1984-85, he worked as a fellow at the Academy of Fine Arts in Warsaw, in Ryszard Winiarski's workshop. In 1979, he started teaching at the Institute of Art Education of his alma mater. Mikołaj Smoczyński was known for creating site-specific installations and black and white photographs resembling abstract paintings. In his works, he focused on the specifics of the material he was applying as well as on matters relating to place and space. The essence of his art lay in capturing an individual's experience in reference to reality in flux.
Smoczyński's early painting works were inspired by American abstractionists, predominantly Franz Kline. He also felt a strong affinity with such styles as minimalism and Arte Povera.
The artist decided to start documenting these altered states of space, considering photography to be the most appropriate medium for doing so. For a period of time, Smoczyński created installations in his studio, solely for the purpose of photographing them, such as in the series The Secret Performance. He carried out these kinds of actions during Martial Law. Being able to concentrate on a personal, internal experience allowed him to cut himself off from the unacceptable reality outside of his working space.
From 1992 onwards, Smoczyński created installations that turned him into an architect of space – he didn't want to transform existing constructions, but to create brand new ones. In the process he used an actual construction material – suprema, which came in modules, suitable for shaping desired structures. The colour and texture of a construction are affected by light, which was the fundamental factor in all of the artist's works. Its dramaturgy exposed the rhythm of Smoczyński's realizations and took over the emerging forms.
Some of the works in which Smoczyński used suprema include Parallel Action (Akcja Równoległa), realized at the Stara Gallery in Lublin in 1992, and Temporary Con Temporary, made in the same year, at the ZPAP Gallery in Warsaw.