The 30-year-old model has taken to her Instagram account to heap praise on the Compton-born beauty, saying she's proud of Danielle for helping break down boundaries by becoming only the third black woman to appear on the cover of the iconic magazine.
Alongside a photograph of the cover, Ashley wrote: ''DANIELLE!!!! Tears of joy for you this morning! Congratulations on breaking even MORE barriers being the 3rd black woman to ever grace the cover of @si_swimsuit! I have so many emotions SOAR BABY GIRL!! @danielle_herrington_ (sic)''
Tyra Banks and singer Beyonce are the only other black stars who have appeared on the front cover of the magazine.
Meanwhile, Ashley has also been credited with breaking down boundaries within the fashion industry, becoming one of the world's best-known plus-size models.
And the brunette beauty recently revealed that her mother Linda has been a central figure in her career, giving her the confidence she needed to pursue her ambitions.
She shared: ''My mom has been my role model since childhood and has played a vital role in developing my confidence. She promoted body positivity in our household before it was a movement.''
Ashley and Linda have similarly curvy figures, and Ashley previously admitted to feeling inspired by her mother's self-assured outlook.
Of her influence, she said: ''Her feel-good attitude toward her own body has shaped my ability to remain positive and self-assured.''
'Smalls Change (Meditations Upon Ageing)' arrives in April.