On Tuesday, the rocker took to Facebook to post a raw and heartfelt tribute to Scott, who was 49.
"I am still struggling to understand how my lover and best friend could end her life in this tragic way" he wrote. "We spent many wonderful years together and had made a great life for ourselves."
He added, "She had great presence and her talent was much admired, not least by me," before singling out the massive outpouring of support that has flooded in: "I have been touched by the tributes that people have paid to her, and also the personal messages of support that I have received."
The rocker then closed out his message with, "I will never forget her."
Scott, who had dressed stars like Nicole Kidman and Sarah Jessica Parker, was found dead inside her Manhattan apartment on Monday morning. An investigation is currently ongoing.
Following the news of her death, Jagger's band, The Rolling Stones, has postponed its upcoming tour dates in Australia.