Sebastian Coe pipped Sergey Bubka in a tight vote to become world athletics chief on Wednesday and vowed "zero tolerance" for drug cheats, who have thrown the sport into turmoil.
The British former Olympic champion runner received 115 votes to Bubka's 92, and will take over from 82-year-old IAAF president Lamine Diack with the fight against doping at the top of his agenda.
Coe likened his victory, at an International Association of Athletics Federations (IAAF) Congress in Beijing, to celebrating the birth of his four children.
"For most of us in this room, we would conclude that the birth of our children is a big moment in our lives, probably the biggest," London-born Coe, 58, told the congress.
"But I have to say that being given the opportunity to work with all of you and shape the future of our sport is probably the second biggest and (most) momentous occasion of my life.
"It's my sport, it's my passion and it's the thing that I've always wanted to do."
After a series of doping controversies rocked the build-up to the August 22-30 world championships in Beijing, the Briton said he and his new team would be "vigilant" in their crusade against cheats.
"There is a zero tolerance to abuse of doping in my sport and I will maintain that to the very highest level of vigilance," vowed Coe, who won Olympic 1500m golds in the 1980 and 1984 Games.
"I don't want the thought that trust and integrity are only something that are rooted in challenges around doping in sport or doping in track and field. There is a universal problem with that in sport and we recognise that and we've been the lead role for that as long as I've been in the sport.
"That's something I'm very proud of, that's something I'll very happily defend, how we approached that."
- Media 'monster' -
Bubka had also stood for re-election as IAAF vice-president, and the pole vault great from Ukraine was duly voted in to the post along with Qatari Dahlan al-Hamad, Cameroon's Hamad Kalkaba Malboum and Cuban Alberto Juantorena.
"This is my life. I continue to serve athletics with dignity and big passion," said Bubka.
"I am a happy man... it was a great and interesting campaign, which is really important for this sport."
Diack said track and field would prosper with one of athletics' "bona fide sons" Coe, whose election victory came 34 years to the day after he set the world record in the 1500m in Zurich.
Coe's first job as IAAF president will be to defend athletics from stinging allegations of widespread doping which threaten to cast a dark cloud over the world championships which kick off on Saturday.
The credibility of both athletics and the IAAF has come under repeated attack in recent weeks, after British and German media said a leaked database of 12,000 tests had revealed "extraordinary" levels of doping.
The IAAF slammed the allegations as "sensationalist and confusing" and also dismissed a later Sunday Times report that it blocked the publication of a document showing extensive doping among top athletes.
Diack, in his outgoing speech, again rounded on the media's portrayal of doping in athletics.
"We have the world championships here in Beijing and people will say 80 percent of the athletes are bound to test positive. That's absolutely not true," he said.
Diack added: "For weeks, people are talking about doping in athletics, the sport has turned into a monster in the eyes of newspapers, saying everyone is doped.
"Opinions are swayed in this way."