Brian Hickerson, 29, was detained by police in the early hours of Thursday morning and he spent the remainder of the night behind bars.
He posted $50,000 for his bail and was released later that afternoon.
Sidenote: here are the hidden women and violence numbers. Post continues after video.
Sources close to the couple told TMZ they were out drinking in Hollywood, and when they returned home, there was an altercation that turned physical.
The Sun reports police noticed marks and redness on Panettiere.
Panettiere, 29, and Hickerson started dating in August 2017 after meeting through mutual friends.
It was the same month she split from her former partner, Wladimir Kitschko, after nine years together. They share a daughter, Kaya, 4, who resides with her dad in his native Ukraine.
— Hayden Panettiere (@haydenpanettier) June 3, 2017