The 77-year-old Rolling Stones star posted a photo of his former partner on Twitter and added the caption: "Remembering L'Wren on her birthday."
Jagger did something similar last year to mark her 51st birthday.
The fashion designer was found dead in her New York City apartment on March 17, 2014. Reports suggested she took her own life.
"I am still struggling to understand how my lover and best friend could end her life in this tragic way," Jagger, who dated Scott for over a decade, said in a Facebook post at the time.
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Her death prompted Jagger and his Rolling Stones bandmates to reschedule a string of dates in Australia, so he could fly back to America to help plan Scott's funeral.
He was diagnosed with acute traumatic stress disorder after his girlfriend's death, according to legal papers filed as part of an insurance dispute over the Stones' scrapped Australian and New Zealand tour.
Court documents filed for the dispute suggested the band postponed the tour because Jagger was ordered not to perform for 30 days by a doctor, who diagnosed the rocker with the stress disorder.