[3] After graduating from the Corps of Cadets, he subsequently served as aide to Adam Kazimierz Czartoryski and visited France, England and Italy.

Both were captured by the Russians at the Battle of Maciejowice in 1794 and imprisoned in the Peter and Paul Fortress at St. Petersburg along with Niemcewicz's aide-de-camp named Kuźniewski.

In the years of the Kingdom of Poland Niemcewicz was the central figure of Polish cultural life and his moral influence was sometimes compared with political and military strength of Grand Duke Constantine.

[2][12] On 11 May 1830, he unveiled a new landmark before the Staszic Palace, the seat of the Society of Friends of Science in Warsaw — a monument to Nicolaus Copernicus sculpted by Bertel Thorvaldsen.

[15][16] Niemcewicz's 1817 pamphlet Rok 3333 czyli sen niesłychany (The Year 3333, or an Incredible Dream), first published posthumously in 1858, describes a Poland transformed into a sinister Judeo-Polonia.

The pamphlet has been described as "the first Polish work to develop on a large scale the concept of an organized Jewish conspiracy directly threatening the existing social structure.