In an Instagram post published Wednesday, Spears shared an old photo of her and Britney from more than two decades ago.
"Yup, she rode the bus home with me after my first day of school, cuz she’s the fn best," Spears said of her sister in the caption on the photo, while adding that Britney is her pick for "Woman Crush Wednesday."
View this post on Instagram
Many of Spears' followers have since commented on the post, with the overwhelming majority of them expressing support for Britney.
"She really is the best," one person wrote. "I’m so thankful I’ve been able to Stan her since 1998 she made my life so much better than it would’ve been without her, she deserves the best life has to give."
"Please let her know how much we love and miss her, and when she is ready to comeback we will be right here waiting for her, no matter how long that takes, her well being and Britney Spears the person comes before Britney Spears the superstar.... we love you Britney," the fan added.
"Sending my love and prayers for Britney!! Her true fans are always going to be here waiting for her!! She’s accomplished so much I’m positive she will overcome whatever she’s going through right no," someone else commented. "Tell her not to worry about social media and just to take care of herself for her sons and of course especially for her own sake! We love her!!"
"Your sister is an amazing woman! We all know how sweet, adorable, nice, beautiful and strong she is and so are you. You are so lucky to have each other. Sending love to both [Jamie Lynn Spears] [Britney Spears]," another fan said. "We will always be proud of the Spears sisters and we'll support you forever."
Spears' post comes just a day after it was reported that Britney had checked herself into a mental rehabilitation facility to seek treatment for depression over her father Jamie Spears' deteriorating health.
The Spears family patriarch has been in and out of the hospital since last year due to a ruptured colon. His condition is reportedly not getting much better and this has taken a toll Britney especially.
However, the singer is said to be getting better, and recently posted on her own Instagram account to reassure fans that she has just been taking "time for a little 'me time.' "