Gaga, who has said she also struggles with mental health issues including trauma from a sexual assault by a music producer when she was only 19, spoke about Spears while attending the red-carpet premiere of the film "House of Gucci" in Milan on Saturday.
"She is wildly talented, she is incredibly inspirational and I am just so happy that we get to celebrate today, that she gets to embark on a new phase of her life," Gaga said of Spears.
Her efforts drew international attention as fans pressed for her release from the conservatorship and her situation was highlighted in films.
Gaga, who created the Born this Way Foundation for people struggling with mental health issues, said Spears, a former teen phenom who became an international pop star, was not treated well by the music industry after a breakdown in which she shaved her head and soon after entered a rehab centre.
In fighting to be released from the conservatorship, Spears "authored her freedom," Gaga said. "She worked hard for this moment and I hope she feels that.”