The 27-year-old former heptathlete and long jumper produced a mark of 14.98 metres to see off Caterine Ibarguen of Colombia and Ukraine's world and double European champion Olha Saladuha who took silver and bronze respectively.
Rypakova, who won silver at last year's world championships, set the winning mark with her third attempt, finishing the night 18 centimetres clear of Ibarguen. Rypakova's previous season's best was 14.84.
Ukraine's Saladuha, a strong favourite to take gold in London having produced four of the top 10 best jumps this year, looked to have catapulted herself into the medal places with her last jump of 14.79 that put her second.
But it was not to be as Ibarguen, who had occupied the silver medal position for most of the night, went one centimetre better to reclaim second and push Saladuha into bronze.
All three medallists finished on the podium at last year's world championships in Daegu, South Korea.
Russia's Tatyana Lebedeva, who has two silver and one bronze Olympic medals, finished 10th and announced shortly after that she would retire, while Britain's oldest female Olympic track and field debutant Yamile Aldama, who turns 40 this month, ended fifth.
