The couple reportedly split earlier this year, but a London-based law firm only released a statement today announcing the pending divorce, saying it is "entirely amicable and is by mutual agreement."
"Both parties are fully committed to the future joint parenting of their children," the statement said.
Married in a beach ceremony in 2003, the same year their son Joe was born, the couple became Hollywood royalty, with scores of nominations and awards for their work. Together they also raised Kate's daughter Mia, from her first marriage to Jim Threapolton.
Mendes, an Oscar-winning director for 1999's "American Beauty" and Winslet, who won the Academy Award in 2009 for her role in "The Reader," were not seen together at this year's Academy Awards.
Before her 2009 win, Winslet had been nominated five times for roles in "Titanic," "Sense and Sensibility," "Iris," "Eternal Sunshine of the Spotless Mind" and "Little Children."
Mendes directed his wife in 2008's "Revolutionary Road," in which she played a bored suburban housewife against Leonardo DiCaprio. Mendes directed the two, who first starred together in "Titanic," in a racy sex scene.
Upon winning a Golden Globe for her role in "Revolutionary Road," Winslet thanked Mendes, whom she affectionately called "babe."
"Thank you for directing this film, babe, and thank you for killing us every single day and really enjoying us actually being in such horrific pain," she said.
Famously superstitious, Winslet and Mendes vowed never to fly on the the same plane together after Sept. 11, 2001. Mendes nearly boarded American Airlines flight 77 that morning, the plane that was crashed into the Pentagon.
The shapely Winslet, who was often asked about body image, was seen over the weekend in Mexico wearing a bikini – without Mendes.