The successful deployment of a first regiment of hypersonic nuclear-capable missiles is an advance which President Vladimir Putin has boasted puts his country in a class of its own.
The location was not given, although officials had earlier indicated they would be deployed in the Urals.
Putin has said the nuclear-capable missiles can travel at more than 20 times the speed of sound and will put Russia ahead of other nations.
They have a "glide system" that affords great manoeuvrability and could make them impossible to defend against.
Defence Minister Sergei Shoigu confirmed the "Avangard hypersonic glide vehicle entered service at 10:00 Moscow time on 27 December", calling it a "landmark event".
Putin said on Tuesday the Avangard system could penetrate current and future missile defence systems, adding: "Not a single country possesses hypersonic weapons, let alone continental-range hypersonic weapons."
The West and other nations were "playing catch-up with us", he said.
Watch this BBC video of images supplied by the Russian Defence Ministry
Some Western experts have questioned how advanced some of the weapons programmes are.
The Pentagon said in a statement that it "will not characterise the Russian claims" about the Avangard's capabilities. The United States has been developing hypersonic weapons since the early 2000s, according to a Congressional Research Service report published in July.
Russia said on 26 November that US experts had examined an Avangard under the inspection rules of the 2010 New START treaty. A US State Department official confirmed that inspectors examined an Avangard, but had no further comment.
Hypersonic glide vehicles are boosted on a rocket to altitudes of between 40km and 100km before detaching to glide along the upper atmosphere towards their target, say researchers.
Control surfaces on glide vehicles mean they can steer an unpredictable course and manoeuvre sharply as they approach impact. They also follow a much flatter and lower trajectory than the high, arching path of a ballistic missile.
That makes them much harder to detect early with radar, giving missile defences less time to respond, say researchers.
However, Jeffrey Lewis, an arms control expert at the Middlebury Institute of International Studies in Monterey, California, said he doubted the claim that the Avangard can evade missile defences. He remains sceptical that gliders will change the survivability of Russia's nuclear forces since gliding results in slower speeds than traditional re-entry, he said.