In a ruling late Wednesday, the panel stayed a district court injunction that had paused the law while the judges consider an appeal of the lower court's move.
The decision, which was supported by two unnamed judges and was not immediately published with the court's reasoning, comes after a Monday hearing in which the jurists appeared to struggle with basic tech concepts, including whether Twitter counts as a website.
The decision is a win for conservative critics of the current interpretation of tech law, which underlies the operations of social media platforms such as Twitter and Facebook. Two tech trade groups that count the Big Tech companies as members had sued Texas over the law.
Until this week, industry observers widely expected the court to uphold a block on the law, which allows for lawsuits against social media services if they "censor" users. A different federal court also paused a similar Florida law, finding that it sought to punish private companies for their views and treatment of content in violation of the First Amendment.
In court, Texas argued that it is merely trying to force platforms to carry all content the way phone companies are expected to carry all calls.
Despite no prior history of courts and lawmakers treating social media as "common carriers" the way phone companies are, and the clear Supreme Court precedent arguing against government interference with internet content, some conservatives have increasingly argued for treating platforms that host user-generated content similarly.
Civil liberties experts and tech advocates argue that such treatment — even with exceptions for obscenity or spam — would poison the online environment, forcing companies to leave up hate speech, harassment, harmful misinformation and more.
"Given the stakes, we'll absolutely be appealing," a lawyer representing NetChoice, one of the organizations that filed the suit against the Texas law, said in a tweet. "HB 20 is unconstitutional through and through."
The decision also comes as many on the right celebrate Elon Musk's expected takeover of Twitter and his plans to scale back content moderation and restore former President Donald Trump to the site.