Cooper, 28, announced the news Monday on social media alongside a photo of the couple at the Ventura County courthouse in California.
“Scarlett and I have made it officially legal and the two of us could not be happier,” Cooper captioned his post, which also includes a slideshow of photos of the pair over the years. “Cheers to a life full of love, happiness, adventure, and great purpose, Mrs. Hefner.”
“I love you dearly and very much look forward to planning our wedding celebrations in the months ahead,” he added. “I love you, Scarlett.”
Scarlett, who played Pansy Parkinson in the Harry Potter franchise films Half-Blood Prince and Deathly Hallows: Part 1 and Part 2, also posted about the news.
“Cooper and I are excited to share that we legally married,” the 29-year-old actress captioned the same courthouse photo of the couple. “We are looking forward to planning our wedding in the coming months where we will celebrate further with our friends and family.”
“I love you Cooper,” she added. “I am proud to stand by your side, as your partner, your friend, and your wife. I cannot wait to continue building a life together. My heart is so full and I am so grateful for our love.:
Cooper announced their engagement on Instagram in August 2015 with a collage of photos, including one of Scarlett’s yellow diamond ring.
“To many more adventures with this lovely lady,” he wrote at the time.
In 2016, Cooper, who joined the family business at the age of 21, was named chief creative officer of Playboy Enterprises, with plans to rebrand the company for his own generation.
In January 2019, he assumed the role of Playboy Enterprises’ chief of global partnerships, but in April confirmed to The Hollywood Reporter that he was stepping down to launch his own digital media platform.
At the time, he had planned to call it HefPost, but on his social media accounts he now lists himself as the CEO of StagDaily, which is expected to launch in 2020.