David Cameron has welcomed the election of Lord Coe as the next president of the International Association of Athletics Federations.
The Prime Minister said he was "delighted" the renowned middle-distance runner - who was a Tory MP and chief of staff to William Hague - would head the sport's governing body.
In a congratulatory message on Twitter, the PM called him "an outstanding athlete who delivered the brilliant London 2012 Olympics".
The two-time Olympic 1500 metres champion, who chaired the successful staging of the Games in the capital, saw off the challenge of Ukrainian Sergey Bubka in a vote at the IAAF Congress in Beijing.
By a margin of 115 member federations to 92, he was handed the tough task of leading the IAAF's response to criticisms it has failed properly to deal with performance-enhancing drug use.
Lord Coe, who has been backed by Mo Farah to "change athletics", has promised to set up an independent anti-doping agency for the sport inside his first 100 days in office.
He described taking on the new role as "probably the second biggest and most momentous occasion in my life" after the birth of his children - ranking it even above his notable successes on the track.
It comes 23 years after he was elected to represent Falmouth in the 1992 general election - a seat he lost in the Labour landslide five years later before he received a peerage in 2000.
While working for then party leader Mr Hague, the pair famously took part in regular weekly judo sessions.
UK Athletics chairman Ed Warner said Lord Coe had been "very vociferous in speaking out against cheats" in the sport.
He told BBC Radio 4's Today programme: "We nominated Seb for the position because we believe he has got all sorts of qualities, included in that masses of integrity when it comes to anti-doping."
He added: "I do believe that he is the right person to get to the heart of the problem, but you can't get away from the fact that ... there have always been cheats in this sport and in many sports and probably will be for decades to come.
"It is an arms race and we need to devote greater resources, and we need independent spending of that money and Seb has put that at the heart of his manifesto."
He went on: "Even one cheat is one cheat too many in my book. We have to be seen to be aggressive and vigilant and to shine a harsh spotlight on cheats wherever we find them."
Mr Warner said Lord Coe was "relishing" the new role.
He said: "He has got an amazing ability to handle a lot at once and appear to do it with aplomb and I'm sure he'll bring those skills to this job, it's a critical job for sport in the UK, not just for athletics."