He was awarded the 1500 m gold medal at the 2008 Summer Olympics after the original winner, Rashid Ramzi, tested positive for doping.

[9] However, Kiprop was awarded the gold medal after Ramzi tested positive for CERA, a banned substance which is a newer version of the more commonly known EPO.

[12] He ended the year with a silver medal at the 2008 IAAF World Athletics Final, finishing behind the African champion Haron Keitany.

[14] He competed on the 2010 IAAF Diamond League circuit that year and after victories at the Bislett Games, Prefontaine Classic and British Grand Prix, he went on to secure the inaugural 1500 m Diamond League title with a win at the final event at the Memorial van Damme.

[15] He ran at the 2011 Great Edinburgh Cross Country in January, taking second place in the short race behind Eliud Kipchoge.

Kiprop was leading in the rankings of the 2011 IAAF Diamond League, having won at the Bislett Games Dream Mile and placed second at the Shanghai, Paris and Stockholm meets.

However, at the event final at the Weltklasse Zürich, he managed only seventh while Nixon Chepseba won to take the seasonal title.

[18] In July 2013, he won the Herculis (Monaco Diamond League) 1500 in a time of 3:27.72, making him the fourth fastest man ever at the distance yet still not achieving the meet record.

[21] Kiprop maintained that he would fight to prove his innocence, but he was found guilty and given a four-year doping ban in April 2019.

His father David Kebenei was also an athlete, who participated in the 1987 All-Africa Games in Kenya and finished fourth in the 1500 metres race.

This led to a release of a semi-nude show that publicly displayed the adultery between Kiprop and his friend's wife.