Timberlake, 40, recently spoke out in support of Spears, posting a tweet about the unfair nature of the conservatorship she is under.
"Regardless of our past, good and bad, and no matter how long ago it was ... what's happening to her is just not right.
"No woman should ever be restricted from making decisions about her own body," he added.
JT continued: "No one should EVER be held against their will ... or ever have to ask permission to access everything they've worked so hard for."
Last week Britney Spears' father Jamie Spears finally agreed to step down as her conservator.
Legal documents have revealed that he has agreed to release control of Britney's finances and personal life and wants to "work with the court on an orderly transition", according to TMZ.