"An event authorized by Moscow authorities with around 4,500 participants has been taking place in the city's center," a spokesman said.
Security and public order have been ensured by the police and the Russian National Guard (Rosgvardia).
READ MORE: Russian Opposition Figure Nemtsov's Killer Sentenced to 20 Years in Prison
On February 14, Moscow authorities agreed to allow the march proceeding from Pushkinskaya Square via Tverskoy Boulevard to Academician Sakharov Avenue in the Moscow center. The same route was used last year.
Nemtsov occupied a number of senior positions in the Russian government in the 1990s and was an active opposition figure in the 2000s. He was shot dead in downtown Moscow on February 27, 2015, while walking with a friend.