World record holder Lashmanova secured a first world title by edging out team mate Anisya Kirdyapkina by just three seconds after clocking 1:27:08 on a hot morning in the capital.
The 21-year-old should have won by a greater margin, but twice almost broke stride after getting confused as to where the finish line was on her final lap in the Luzhniki stadium.
The hosts were denied a podium sweep after Vera Sokolova, who was in third place, was shown a third yellow card and disqualified soon after entering the arena with just over one lap of the track to complete.
Her mishap allowed China's Liu Hong, a world silver medallist in 2011, to take bronze in 1:28.10.
Russia's triple world champion Olga Kaniskina, beaten to Olympic gold by Lashmanova in London last year, pulled out of the event on the eve of the championships.
Russia also won men's 20km walk gold on Sunday when Aleksandr Ivanov triumphed.