The Heroes and Nashville actor posted to the social media website to share a photograph of a new hairstyle.
The last post from Panettiere was back in April when she shared some news about the Disney Plus film Secrets of the Whales.
Panettiere has not acted since Nashville, which aired its final episode in 2018.
Last year, Panettiere shared the phone number for a domestic abuse hotline, saying said she hopes to “empower others” after her ex-boyfriend Brian Hickerson was arrested and charged with felony assault.
Following reports of Hickerson’s arrest, Panettiere addressed the alleged abuse during their year-and-a-half-long relationship in a statement shared to Twitter.
“I am coming forward with the truth about what happened to me with the hope that my story will empower others in abusive relationships to get the help they need and deserve,” the 30-year-old wrote. “I am prepared to do my part to make sure this man never hurts anyone again.
“I’m grateful for my support system, which helped me find the courage to regain my voice and my life.”
Panettiere attached an online link and phone number for an abuse hotline, concluding: “You are not alone.”
In a statement shared with People, Panettiere’s attorney said she had “begun the process of taking back her life” after “suffering for years as the victim of psychological, emotional and severe physical abuse”.
“Hayden has found the strength and courage to share the truth about her abuse and her abuser, and she intends to assist the prosecution to see that justice is served. As a survivor, she recognises that her arduous journey of healing has just begun,” the statement read.
Access unlimited streaming of movies and TV shows with Amazon Prime Video Sign up now for a 30-day free trialSign up
The arrest came after Panettiere filed a restraining order against Hickerson, five months after he was arrested in Jackson, Wyoming, and charged with domestic battery and interference with a cop, according to People. Hickerson pleaded not guilty to the charge.
In April, Hickerson was sentenced to 45 days in jail on two felony counts of injuring a spouse or girlfriend. In addition to the sentence, he was given four years of formal probation, ordered to attend domestic violence classes and give a restitution.
You can contact the National Helpline for rape and sexual abuse, provided by Rape Crisis South London, by calling 0808 802 9999. The helpline is open between 12 and 2.30pm and 7 and 9.30pm every day of the year.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies