Mr Putin was speaking in a pre-recorded video address shown to attendees at the conference, including Russian military officials and their counterparts from countries in Asia, the Middle East and Africa.
He said western countries were “pumping billions of dollars” into Ukraine and “supplying it with equipment, weapons, ammunition, sending their military advisers and mercenaries.”
“Everything is being done to ignite the conflict even more, to draw other states into it,” Mr Putin said.
Russia also displayed a range of armoured vehicles at the conference, which it claimed to have seized from Ukraine.
Defence Minister Sergey Shoigu sought to downplay the significance of the West's support for Ukraine, saying that in spite of this aid, Kyiv's forces “fail to achieve results on the battlefield.”
Russia claimed that Ukraine's military resources were "almost exhausted" as Kyiv pursues a counter-offensive to regain its lost territory.
Mr Shoigu said the western aid was "nothing unique" and was not "invulnerable to Russian weapons on the battlefield today".
He claimed that "in many cases, even Soviet-manufactured hardware is superior in its combat qualities to western models".
Ukraine and its allies have likewise reported Russian equipment problems since Moscow launched its invasion in February 2022.
Algeria's chief of defence staff Said Chengriha, who spoke on a panel on the Middle East and Africa, said his country opposed military intervention in Niger and believed it necessary to resolve the crisis through diplomacy, according to Russian media. Representatives of Iran and Syria also addressed the conference.
"Crises on the African continent have become more varied in intensity and intricacy, evolving in terms of their sources and influencers," Mr Chengriha said.
"We are witnessing an upsurge in internal disputes, civil wars, both overt and covert foreign interventions, and an intensified strategic competition by major powers over the continent's natural and mineral resources to position themselves in line with their agendas," he added.
Seeking allies in Africa, Russian Foreign Minister Sergey Lavrov said the West had responded to a Moscow-friendly coup in Niger by "demanding the restoration of democracy by almost any means".
Mr Shoigu blamed Ukraine for the collapse of the Black Sea grain deal - which Russia torpedoed last month by refusing to extend the UN-backed agreement.
He claimed Ukraine had "created substantial stocks of weapons and ammunition in Odesa and other Black Sea ports, which are systematically supplied to the front".
The UN has urged Russia to return to the deal amid fears that a renewed Black Sea blockade will worsen food insecurity in Africa.
Moscow also accused Ukraine of subjecting the Zaporizhzhia nuclear power plant to "regular shelling with heavy weapons".
The actions of Ukraine's armed forces "could provoke a nuclear catastrophe", Mr Shoigu said at the conference.
Ukraine blames Russian troops, who have occupied the Zaporizhzhia site since the war's early stages, for the threats to the plant.