Video footage shows the 67-year-old tripping and falling on his hands and knees at the at the 'Russia the Land of Opportunities' forum.
The Foreign Minister picked himself up awkwardly, and later joked; 'I tripped. It's good it was not on a diplomatic front but on a step.'
His fall came after he slammed Britain over the spy row which has erupted in the wake of the poisoning of former double-agent Sergei Skripal and his daughter Yulia in Salisbury, Wiltshire.
Lavrov condemned claims Russia was behind the assassination attempt on March 4 as 'absolutely boorish' and 'unacceptable'.
The Foreign Minister accused Britain of trying to to cover up the absence of 'facts' by 'fanning anti-Russian rhetoric bordering on hysteria' in an attempt to rally support from its allies.
He also charged that the 'provocation with Skripal' helps British Cabinet distract public attention from its failure to secure a Brexit deal.
He claimed that Russia's enemies were seeking to use the incident to try to derail the this summer's football World Cup
Lavrov said Moscow expects London to abide by procedures of the international chemical weapons watchdog to investigate.
Russia is expected to expel British diplomats from Moscow in retaliation for British Prime Minister Theresa May's announcement that she was kicking 23 spies out of Britain over the Skripal poisoning row.