In a series of tweets, Timberlake wrote that he and wife Jessica Biel send their love and “absolute support to Britney during this time.”
“Regardless of our past, good and bad, and no matter how long ago it was… what’s happening to her is just not right,” Timberlake added.
In a court hearing Wednesday, Spears accused her conservators, including her father Jamie, of forcing her to take lithium to the point she felt drunk and coercing her to perform when she didn’t want to.
The pop star, 39, said in remote testimony that she was denied access to a doctor to have her birth-control device removed so she could have another child.
“No woman should ever be restricted from making decisions about her own body,” Timberlake commented.
Spears said her handlers’ control has been traumatizing and abusive, suggesting she was imprisoned in her own life.
“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.
“We hope the courts, and her family make this right and let her live however she wants to live.”
Spears has been under the conservatorship since 2008, after mental health issues.
Timberlake and Spears, former co-stars on Disney’s “Mickey Mouse Club,” famously dated from 1999 to 2002.
Earlier this year, an apologetic Timberlake said he had “failed” to support Spears after a new documentary “Framing Britney Spears” depicted him as lacking compassion. Spears’ fans also resented his “Cry Me A River” music video, which many believe accused Spears of cheating on him and cast her as a villain in the relationship.
“I think everyone has a side of their story, to make them feel a certain way,” Spears said in a 2003 interview.