In a New Year's message published on the International Olympic Committee website (www.olympic.org), the IOC president looked forward to the 2016 Summer Games in Rio de Janeiro but warned of big challenges ahead.
"When Olympic Agenda 2020 was adopted one year ago, my message to everyone in the Olympic Movement was: change or be changed," the German said, referring to the reforms he championed.
"One just needs to look at the events over the last 12 months to realise that this message is even more urgent today to safeguard the credibility of sports organisations and to protect clean athletes.
"Undoubtedly, recent developments in some sports cast a shadow across the whole world of sport," continued Bach, without mentioning world soccer body FIFA or the International Association of Athletics Federations (IAAF).
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FIFA, whose president Sepp Blatter has been banned for eight years, is embroiled in the worst graft scandal of its history, with criminal investigations in the United States and Switzerland.
Soccer bosses from across South and Central America have also been charged by the United States with multi-million-dollar bribery schemes for marketing and broadcast rights, bringing the number of indictments so far to 41.
In athletics, former IAAF president Lamine Diack and his son Papa Massata Diack are under investigation over corruption offences, while Russian athletes are currently banned from the sport following revelations of widespread, state-sponsored doping.
European Athletics president Svein Arne Hansen said on Tuesday he did not expect Russia to return to international competition in time for the Rio Games in August.
"As the role and relevance of sport in society continues to grow, so do the expectations of the public vis-a-vis the integrity of athletes and sports organisations," said Bach.
"It is our shared responsibility in the Olympic Movement to provide new answers to new questions."
Bach added that the IOC expected "all sports organisations to follow our lead".
"Our process of change continues in 2016 with the same energy and determination," he said.
Turning to Rio, Bach said the economic and political situation in Brazil would make the final months of preparations more challenging but he was confident the country would welcome the world enthusiastically.
Brazil is enduring its worst recession in 25 years, with rising unemployment and inflation, as well as a massive corruption scandal involving state oil company Petrobras.
(Reporting by Alan Baldwin, editing by Pritha Sarkar)
