"Two weeks ago I asked my soulmate to marry me and she said yes xx I am the luckiest man in the world. I promise to be the best husband and the best daddy one day ❤️ I love you baby xx," Brooklyn wrote on Instagram on Saturday alongside a photo of him and Peltz, who is flashing her new engagement ring.
Peltz posted a similar photo, writing, "You’ve made me the luckiest girl in the world. I can’t wait to spend the rest of my life by your side. Your love is the most precious gift. I love you so so much baby and thank you Harper for this pic ?."
ET has reached out to the couple's reps for comment.
Beckham, who is Victoria and David Beckham's eldest son, and Peltz have been head over heels for one another, posting photos together on social media.
The 21-year-old photographer and the 25-year-old Transformers: Age of Extinction star made their red carpet debut in February of this year, when they attended the Saint Laurent show as part of Paris Fashion Week.
On May 22, Peltz gushed about her beau, writing on Instagram, "I’m dating my best friend and that makes me so happy."
Most recently, Peltz was also with the Beckham family to celebrate the photographer's sister, Harper Beckham's, 9th birthday on Friday. She shared a sweet photo of her and the birthday girl on her Instagram Story. However, there was no visible ring on her finger.