Rhythmic gymnastics: Evgeniya Kanaeva defends Olympic title
The 22-year-old performed several breathtaking routines in the Wembley Arena to finish clear of the field.
Each of the 10 gymnasts competed with the hoop, ball, clubs and ribbon.
Dmitrieva had upstaged her three-time world championship winning team-mate in the opening qualifying round on Thursday, but the usual order was restored in the final.
Kanaeva took a grip of the competition from the first routine as her mastery of her gold-coloured hoop produced a score of 29.350, before she was given a leading 29.200 with the ball.
The clubs provided no obstacle as yet another stellar display was rewarded with 29.450.
Kanaeva's mixture of grace and accuracy ensured Dmitrieva headed into her last routine knowing not even a perfect score would win gold.