Sedov won a gold medal for the 94 kg class at the 2009 World Weightlifting Championships in Goyang, South Korea, with a total of 402 kg, defeating Azerbaijan's Nizami Pashayev by fifteen kilograms.

[1] Sedov represented Kazakhstan at the 2008 Summer Olympics in Beijing, where he competed for the men's light heavyweight class (85 kg).

Sedov, however, narrowly lost the Olympic medal to Armenia's Tigran Vardan Martirosyan by three kilograms short of his record from the clean and jerk, finishing the entire event in fourth place.

[2][3] On 17 November 2016, the IOC disqualified him from the 2008 Olympic Games and struck his results from the record for failing a drugs test in a re-analysis of his doping sample from 2008.

Weightlifting at the 2008 Summer Olympics – Men's 85 kg – he finished fourth, but was disqualified after he tested positive for stanozolol.