The "Global Corruption Barometer" is the biggest ever conducted by the Berlin-based watchdog, with 114,000 people responding in 107 countries in the survey of opinions on corruption and which institutions are considered most corrupt.
The survey found that on a worldwide basis political parties are considered to be the most corrupt institution, scoring 3.8 on a scale of 5 where 1 means "not at all corrupt" and 5 means "extremely corrupt."
Only 23% of those surveyed believed their government's efforts to fight corruption were effective, down from 32% in 2008.
"Politicians themselves have much to do to regain trust," Transparency International said in a release. "(The Barometer) shows a crisis of trust in politics and real concern about the capacity of those institutions responsible for bringing criminals to justice."
The second most corrupt institution on a global scale is the police with a score of 3.7. Three categories of institutions - public officials/civil servants, parliament/legislature and judiciary - followed with equal scores of 3.6.
"It is the actors that are supposed to be running countries and upholding the rule of law that are seen as the most corrupt, judged to be abusing their positions of power and acting in their own interests rather than for the citizens they are there to represent and serve," Transparency International wrote.
The media did not fare as badly, coming in at the ninth place out of twelve with a score of 3.1, but it was seen as the most corrupt in Australia and Britain.
Some 69% said it was the most corrupt institution in Britain, up from 39% three years ago.