The 41-year-old British-born star’s last three films made $44 for every $1 she was paid to appear Watts came out.
On top after Forbes magazine analyzed the salaries and box office returns of the top 100 female stars in Hollywood.
The worldwide success of King Kong in 2005, and last year’s well received The International, helped Watts to beat actresses who receive bigger pay cheques such.
As Julia Roberts and Angelina Jolie. To qualify for the list actresses had to have starred in three films in the last five years and those releases had to have opened in at least 500 cinemas.
The amount the films made was then compared to the amount of money the actress cost to give a “return on investment” (ROI).
The list will be keenly studied by studios struggling to pay out the huge amounts required to cast major stars.
Watts was born in Kent and moved to Australia with her family as a teenager. She began her acting career on Australian television, including the soap opera Home and Away. In 2003 she was nominated for an Oscar for her role in 21 Grams.
Jennifer Connelly was the second most bankable actress, according to the Forbes list. The 38-year-old American was helped by the surprise hit He’s Just Not That Into You, which earned $177 million (£111 million). Several stars took a pay cut to appear in the ensemble cast, according to Forbes.
Connelly also starred in The Day The Earth Stood Still and Blood Diamond, alongside Leonardo DiCaprio. For every dollar she earned her films took in $41. Canadian actress Rachel McAdams, 30, was third after appearing in several relatively low budget films which did well at the box office, including Red Eye and The Notebook.
Despite her stellar status Meryl Streep also featured in the top 10 with her films earning $27 for every dollar she was paid. They included the huge hit Mamma Mia which earned $610 million (£382).
Jennifer Aniston was ranked the sixth best value actress thanks to the success of He’s Just Not That Into You and Marley & Me. And despite her most recent film flopping Halle Berry also made the list thanks to the success of the X-Men series.
Top 10 actresses and their ROI
Naomi Watts 44
Jennifer Connelly 41
Rachel McAdams 30
Natalie Portman 28
Meryl Streep 27
Jennifer Aniston 26
Halle Berry 23
Cate Blanchett 23
Anne Hathaway 23
Hilary Swank 23