Shelley Luther, owner of Salon à la Mode in Dallas, appeared in court on Tuesday after defying a cease-and-desist letter and a restraining order.
The judge said she could avoid jail if she apologised for being selfish, shut the salon and paid a fine.
But Luther refused, saying "feeding my kids is not selfish".
She would only have needed to close the salon until Friday, because the state plans to allow them to reopen then.
Luther was fined $7,000 (£5,652) and warned that she would be fined a further $500 a day from now until Friday if the business continued to remain open.
Judge Eric Moyé told Luther: "The rule of law governs us. People cannot take it upon themselves to determine what they will and will not do."
A Dallas inspector and a police officer told the court that they saw clients inside getting haircuts and manicures, according to the Texas Tribune.
On 25 April, Luther was pictured at a rally to reopen the state, ripping up a cease-and-desist letter that had been handed to her.
Last week, she told her followers on Facebook that she had a right to remain open.
In court she told the judge: "I have to disagree with you, sir, when you say that I am selfish, because feeding my kids is not selfish. I have hair stylists that are going hungry because they'd rather feed their kids.
"So, sir, if you think the law is more important than kids being fed, then please go ahead with your decision. But I'm not going to shut the salon."
Source : BBC