"After what we saw today, we should all be supporting Britney at this time," the 40-year-old singer wrote on Twitter, before alluding to their tumultuous courtship in the early 2000s. "Regardless of our past, good and bad, and no matter how long ago it was… what’s happening to her is just not right."
During her 20-minute speech in court, Spears made a series of shocking revelations and condemned her conservatorship and those in control of her life and finances.
Spears told Judge Brenda Penny that she's forced to use an intrauterine device (IUD), despite wanting to have more children. "I was told right now in the conservatorship, I’m not able to get married or have a baby," Spears said. "I have (an) IUD inside of (me) right now so I don’t get pregnant."
Timberlake addressed Spears' comments in his tweet, adding: "No woman should ever be restricted from making decisions about her own body."
'I'm so angry it's insane':Britney Spears says she's 'enslaved' in an 'abusive' conservatorship
In another tweet, he wrote: "No one should EVER be held against their will… or ever have to ask permission to access everything they’ve worked so hard for."
Timberlake wrote that he and wife Jessica Biel send "our love" and "absolute support" to the singer. "We hope the courts, and her family make this right and let her live however she wants to live."
Timberlake recently faced backlash for his treatment of Spears following the release of the "Framing Britney Spears" documentary in February.
"I have seen the messages, tags, comments, and concerns and I want to respond. I am deeply sorry for the times in my life where my actions contributed to the problem, where I spoke out of turn, or did not speak up for what was right," Timberlake wrote in a statement posted on Instagram. "I specifically want to apologize to Britney Spears and Janet Jackson both individually, because I care for and respect these women and I know I failed."
Other celebrities also showed their support of Spears on social media.
"We love you Britney!! Stay strong," Mariah Carey tweeted.
Khloé Kardashian tweeted: "No one should be treated like this. Stay strong Queen!! You deserve better … #FreeBritney."
Singer Halsey tweeted she "admire(s) her courage speaking up for herself today."
"Bless Britney and I hope with my whole heart she is awarded freedom from this abusive system. She deserves it more than anything," she wrote.
In a follow-up tweet, Halsey wrote: "Additionally, (expletive) anyone who thinks they have the authority as an institution or individual to control a person’s reproductive health. #FreeBritney."
Meghan McCain asked: "How is what has been done to Britney Spears not a human rights crime?"
"Isolation, controlling her capacity to reproduce without her consent, forcing her to work under inhumane conditions. If she were any other person the people who did this to her would be in jail," she tweeted.
McCain added that she felt "physically sick" about the revelations made during Wednesday's court hearing.
"I think because it's about so much more… Women not being heard, not being trusted, accused of being crazy at any slight deviation from a perfect veneer," she went on. "We as a society have utterly failed her and her dad should be in jail."
Brandy also took to Twitter to show her support of the pop singer, writing: "Sending all my love and support to Britney Spears and her fans."
Rose McGowan, who has in the past been vocal about Spears' conservatorship case, appeared on Fox News' "Tucker Carlson Tonight" Wednesday to rally behind the pop singer.
"Well, in my opinion and in many others', (Britney's conservatorship) is bad," she began. "Her father put her under a conservatorship at age 25. Many in the media laughed and scorned her when she shaved her head.."
McGowan added that the court hearing "is a cultural landmark moment."
"She got to speak for the first time I believe, in her life, honestly and openly," she said. "And what has been done to her, it's horrific."
Wednesday's hearing marked the first time the singer has spoken in court since May 10, 2019. Then, the courtroom was sealed and none of what she said became public.
"A lot has happened since two years ago,” Spears said during the hearing. “I haven’t been back to court because I don’t think I was heard on any level when I came to court last time.”
Contributing: Elise Brisco, Bill Keveney