She began 2012 on grass and came third at the Kenyan Cross Country Championships. This was her preparation for the 2012 London Marathon, where she was the last runner to challenge eventual winner Mary Keitany and ended the race as runner-up in a personal best of 2:19:50 hours. Kiplagat was selected for the Kenyan Olympic team as a result. She was a comfortable winner of the New York Mini 10K in June. At the 2012 London Olympics she failed to repeat her success in the British capital and managed only twentieth place in the Olympic marathon with a time of 2:27:52 hours. Six weeks later she ran at the Great North Run and had a better performance, setting a personal best of 1:07:41 hours while finishing runner-up to Tirunesh Dibaba.