Addressing Russia's military, veterans, and more than 20 international leaders, including China's Xi Jinping, Putin said Russia remembered the lessons of World War Two and declared that "truth and justice are on our side".
He claimed that the whole of Russia backed the war in Ukraine, which he called a "special military operation" - now well into its fourth year, BBC reported.
A unilateral, three-day ceasefire was announced by Russia to coincide with the lavish 80th anniversary event, which Ukraine has rejected as a "theatrical show".
Ukraine's military said it had come under thousands of attacks since the ceasefire came into force on 8 May. Russia has insisted the ceasefire is being observed and accused Ukraine of hundreds of violations.
Heavy restrictions were in place in the center of Moscow as Russia marked the Soviet Union's victory over Nazi Germany.
Before Putin's address and a one-minute silence, the commander of ground troops, Oleg Salyukov, led 11,000 troops into Red Square, where they were inspected by Defence Minister Andrei Belousov.
MNA