The 30-year-old 'Toxic' hitmaker and her finances have been under the legal control of her father Jamie since she suffered a breakdown in 2008.
But her fiance Trawick will be able to have a say on her general wellbeing including where she lives and her medical care, reported People magazine.
Jamie, along with Britney's lawyer Andrew Wallet, will continue to control her financial and business affairs, however, he is said to be pleased about Trawick's inclusion.
"Jamie's thrilled. It's all in the family. The request to add Jason came from Britney and not Jamie," Wallet said.
This decision indicates that sooner or later Britney's third marriage is on cards.
The singer, who has two sons with ex-husband Kevin Federline, is also keen to completely get her conservatorship lifted but that will only happen when doctors consent that she is ready to go alone. PTI GJS JCH