She completed a sweep for Britain in the two finals held at the velodrome with the men's team pursuit squad cracking the world record while defeating Australia for the gold.
Pendleton was the first Olympic winner of the Keirin race, in which a motorcycle paces the cyclists before pulling away and letting them battle it out at high speed for five laps around the track.
On Thursday, Pendleton was judged to have switched places on the track with her teammate at the wrong time during a heat in the team sprint event. That cost the British team a chance to advance and likely cost them a medal.
There were no mistakes this time. Pendleton shot to the front with more than a lap to go and held off the challenge of China's Guo Shuang.
Guo was guilty of the same violation as Pendleton during the team sprint on Thursday, leaving China with the silver medal in that event instead of the gold it originally appeared to have won.
In qualifying for the women's team pursuit Friday, the British squad set a world record of 3:15.669 in the 3,000-meter race. The United States was second quickest.
The men's final in the pursuit race was held Friday and the British established a world mark as well.
Edward Clancy, Geraint Thomas, Steven Burke and Peter Kennaugh turned in a 3:51.659 over 4,000 meters to win their second straight Olympic gold medal.
Australia finished almost three seconds back in the finals while New Zealand defeated Russia for the bronze.