Independent MP Andrew Wilkie used parliamentary privilege in March to claim he had received information that the Australian Football League (AFL) was "secretly" manipulating drug tests to keep players on the pitch.
But government agency Sport Integrity Australia said it had found no evidence to back up Wilkie's allegations, also adding that no breaches of the World Anti-Doping Code were identified.
It did however make several recommendations including the need for independent oversight of the AFL's illicit drugs policy, with the current confidential model creating "a level of suspicion".
The inquiry also suggested bolstering education around doping.
Sport Integrity Australia chief executive David Sharpe said drug use presented a growing challenge to all Australian sports, not just the hugely popular AFL, which is similar to Ireland's Gaelic football.
He cited "criminals influencing sport through the supply of illicit drugs, including by preying on athletes or support staff to access inside information".
"Significant intervention is required immediately to address the illicit drug culture in sport and the increasing and unacceptable risks posed to players, officials, clubs and sporting codes," he added in a statement.
Wilkie, a renowned whistleblower, had claimed players would be urged to fake an injury if they were at risk of testing positive for drugs on game day.
At the time, League boss Andrew Dillon denied the AFL had a drug problem, saying it impacted only "a very small handful of players" each year.
He said on Monday that he had been confident from the outset "that the allegations raised in parliament did not reflect either the intent or operation of the illicit drug policy".
"We take the integrity of our sport extremely seriously," he added.
"It is important to reinforce the point that we do not in any way condone illicit drug use, but we accept that we have a responsibility as a code to try and change behaviours of those that do make the mistake of trying/using illicit drugs."
Australian Rules has a huge fan base and boasts hundreds of millions of dollars in revenue each year.
