Sebastian Coe was elected president of the International Association of Athletics Federations (IAAF) on Wednesday after beating Ukraine's Sergey Bubka by 115 votes to 92 in a ballot of the governing body's 50th Congress.
The Briton takes over as head of a sport battling a public relations crisis with the IAAF accused of failing in its duty to address doping amid allegations that blood doping was rife in athletics.
The former Olympic 1,500 meters champion will replace Senegalese Lamine Diack, who has run the body for the last 16 years, at the end of the Aug. 22-30 world championships in Beijing.
"For most of us in this room, we would conclude the birth of our children are the biggest moments in our lives," said Coe, whose initial term will be for four years.
"I have to say given the opportunity to work with all of you in the future of our sport, is probably the second biggest and momentous occasion in my life."
Former Olympic pole vault champion Bubka congratulated Coe on his victory and was later elected one of four IAAF vice presidents.
"I know athletics will grow and become stronger," Bubka said. "I am a happy man because I love athletics. I will continue to serve athletics with passion. This is my life."
Outgoing president Diack said he was delighted to finally have a successor and in particular one who had dedicated his life to the sport.
"The white-haired generation has done what it could, and now over to the black-haired generation," the 82-year-old said.
Coe has aggressively defended the IAAF's record on doping over the last three weeks, saying the organisation had "led the way" on out-of-competition testing and laboratories, and introduced blood passports in 2009 to help weed out the cheats.
Coe has previously said that under his leadership the sport would move towards setting up its own anti-doping agency.
Your fight is my fight
In speeches to delegates before and after Wednesday's vote, the former politician did not mention doping once, saying only "trust and integrity" were the twin pillars of the sport.
He promised delegates he would empower federations to deliver the kind of sport they wanted, not dictate from its centre.
Coe also reiterated his promise to hand each of the 214 federations a development grant of $200,000 in each Olympic cycle of four years, and to engage with governments to help utilise their funding to help athletes.
The financial acumen he gained in heading up the organising committee for the London Olympics would stand him in good stead as he seeks to bring new sponsorship to the sport, he added.
"All my life I have fought for athletics," said Coe. "I have fought to bring it to my country, I fought to be as good as I could, I fought to take it to young people.
"I fought to make my sport as strong as it could be.
"But I have never done it on any one of those occasions alone. I have always done it together with you my friends.
"I will always be in your corner, your fight is my fight."