10:09 AM PT -- Vanessa is asking fans to honor Gianna today by wearing her favorite color ... red!
"Gianna loved to wear a red bow in all of her school pictures. Red means love and life," Vanessa said.
"To commemorate Gigi’s birthday today, please consider wearing red, caption an act of kindness or show how you will play Gigi’s way since she always gave everything she did her all and led with kindness."
"Please use the hashtag #PlayGigisWay Thank you."
Vanessa Bryant is paying tribute to her daughter, Gianna -- who would have turned 14 years old today ... saying, "You are part of MY SOUL forever."
"Happy 14th Birthday to my sweet baby girl, Gianna," Vanessa posted on social media.
"Mommy loves you more than I can ever show you. You are part of MY SOUL forever. I miss you so much everyday."
"I wish I could wake up and have you here with me. I miss your smile, your hugs and your giggles. I miss EVERYTHING about YOU, Gigi."
Gigi was an unbelievable basketball player with dreams of playing in the WNBA along with her Mamba Academy teammates, Alyssa Altobelli and Payton Chester.
In fact, all 3 of the girls were announced as the first three honorary picks of the 2020 WNBA Draft.
Vanessa said of the Draft ... "It would have been a dream come true for [Gianna]. She worked tirelessly every single day. She wanted to be one of the greatest athletes of all-time, just like her daddy. So thank you, thank you for honoring my little girl."