Senator Darius Brown, who represents part of Wilmington, turned himself in on charges of offensive touching and disorderly conduct on Tuesday.
The 39-year-old is accused of hitting a woman in the side of the face at the Taverna Rustic Italian Restaurant on Sunday.
Police say the two had been arguing about a social media post.
After the attack, Senator Brown allegedly threw a glass of water and left.
Brown left the restaurant before police arrived, according to Delaware State Police.