George Clooney made $322 million last year to become highest-earning actor in world

George Clooney made $US239 million ($322 million) last financial year, the highest annual earnings in his 35-year career.

The Oscar-winning star's earnings were in part due to the sale of the Casamigos tequila company he co-founded to British spirits company Diageo in June 2017, Abc.net.aureports, citing the Forbes Celebrity 100 list.

Forbes compiled the 2018 list estimating pre-tax earnings from June 2017-June 2018, before deducting fees for managers, based on data from Nielsen, touring trade publication Pollstar, movie database IMDB, and interviews with industry experts and celebrities themselves.

Forbes said the sale gave Clooney the best annual earnings of his 35-year career in film and television, and put him second on the list behind American boxer Floyd Mayweather.

Forbes said entertainers on its 2018 Celebrity 100 list earned a combined $US6.3 billion ($8.5 billion) before tax, up 22 per cent from last year's list.

Many of the highest earners came from celebrities leveraging their brands through side ventures and through their social media presence.

"There's never been a more lucrative time to be famous than now, with 11 superstars earning $US100 million ($134 million) or more over the past year," Zack Greenburg, senior entertainment editor at Forbes, said in a statement.

"Entertainers have found all sorts of new ways to monetise their audiences, especially with the help of social media."