The court in Wisconsin granted a stay to a judge's order that Dassey should be released, citing the state's appeal of the order, according to court documents.
"Mr. Dassey will remain in prison pending the outcome of the appeal," Brad Schimel, Wisconsin's attorney general who filed the emergency motion, said in a statement.
Schimel has been countering moves by the US federal judge in Wisconsin, William Duffin, who in August overturned Dassey's murder conviction. Schimel appealed that decision.
On Monday, Duffin ordered the release of Dassey, 27, arguing he should be freed while the appeal of the overturned murder conviction is processed.
Schimel quickly acted to block the release, winning approval by the three-judge appeals court.
Dassey and his uncle Steven Avery were sentenced to life terms in 2007 for the murder of a female photographer, Teresa Halbach, in 2005.
Their story was featured in the Netflix documentary series "Making a Murderer," launched in December 2015. It raised questions about the US legal system and prompted many viewers to believe the pair were unfairly convicted.
Judge Duffin, in his order overturning Dassey's conviction, harshly rebuked the investigating police and Leonard Kachinsky, the public defender appointed in 2006 to represent Dassey -- a 16-year-old minor at the time.
Dassey has intellectual deficits and was unfairly pushed into a confession during a controversial interrogation, and his defense was inadequate, supporters of his release argue.
Following the Netflix series, fans called for the two men to be freed and almost 130,000 people signed a White House petition asking for a presidential pardon.
The White House explained that because the men were not convicted of federal crimes and "are both state prisoners," pardoning them was outside the scope of the president's power.
The documentary was prompted by the unusual story of Avery. He was exonerated of a rape case through DNA evidence and freed from prison in 2003 after serving 18 years behind bars.
Two years later, while he was suing Manitowoc County in Wisconsin over wrongful imprisonment, he was arrested over the death of the 25-year-old Halbach.
