The couple married on New Year's Eve in 1997, and have since had children Jaden Smith and Willow Smith together.
Rumours emerged earlier this year that the pair were splitting up, but both actors have insisted that their marriage is stronger than ever.
Pinkett Smith told People at the premiere of her movie Madagascar 3: Europe's Most Wanted that she and her husband are proud for making the relationship last.
"Fifteen years! It's amazing, isn't it? We celebrate throughout the year," Pinkett explained. "But usually on our wedding anniversary, we give ourselves a high-five and go, 'We survived another year, homie! Yeah!'"
The actress described her marriage to Smith as "a beautiful journey with lots of chapters".
Smith currently stars in another blockbuster, Men In Black 3, while the couple's daughter Willow is gearing up to star in a remake of Annie.
Watch a trailer for Jada Pinkett Smith's Madagascar 3: Europe's Most Wanted below: