The star of Men In Black and Independence Day topped the Forbes Star Currency list, which measures actors' financial clout.
The data was based not just on box office success but also on a star's ability to attract financing and guarantee cinema distribution for a project, and whether or not their presence "significantly drives box office performance".
"Will Smith stands alone as the only actor to score a perfect 10 among industry voters in the Star Currency survey," the magazine said.
The 40-year-old star's films have made $5,239,409,825 (£3,615,342,000) at the worldwide box office. In the US, eight of his movies have debuted in the number one slot at the box office.
Johnny Depp was second in the list, thanks in part to his Pirates of the Caribbean trilogy, although the magazine dubbed him "the poster child for 'indie actor as box office star'". Leonardo DiCaprio was third.
In fourth place, Angelina Jolie was the highest ranked actress - one place ahead of her partner, Brad Pitt. Forbes said: "She's got the acting credibility and exposure - key ingredients. Some of her peers on the upper reaches of the list have more box office to their names, but right now, the industry clearly recognises what she can mean to a project."
Tom Hanks, George Clooney, Denzel Washington, Matt Damon and Jack Nicholson made up the rest of the top 10. Of Nicholson, still going strong at 71, the magazine said: "Iconic. Living-legend status, but still hip with audiences. The three-time Oscar winner has mapped his career in a way few others have."
Julia Roberts and Meryl Streep were the only other females to figure in the top 20.
