Rejecting the Trump administration's request to pause the lower court's order, the three-judge appeals panel ruled the plaintiffs would likely be able to prove that federal agents had carried out arrests based on people's appearance, language and where they lived or worked.
President Donald Trump called National Guard troops and US Marines into Los Angeles in June in response to protests against the immigration raids, marking an extraordinary use of military force to support civilian police operations within the United States.
The city of Los Angeles and other Southern California municipalities joined a lawsuit filed in June by the American Civil Liberties Union, accusing federal agents of using unlawful police tactics such as racial profiling to meet immigration arrest quotas set by the administration.
A California judge in July blocked the Trump administration from racially profiling immigrants as it seeks deportation targets and from denying immigrants' right to access to lawyers during their detention.
In Friday's unsigned decision, the judges of the US Court of Appeals for the Ninth Circuit largely rejected the administration's appeal of the temporary restraining order.
The judges agreed with the lower court in blocking federal officials from detaining people based solely on "apparent race or ethnicity", speaking Spanish or accented English, or being at locations such as a "bus stop, car wash, tow yard, day labourer pick up site, agricultural site, etc".
The Department of Homeland Security and US Immigration and Customs Enforcement did not immediately respond to requests for comment outside business hours.
Los Angeles Mayor Karen Bass called the order a victory for the city.Â
"The Temporary Restraining Order that has been protecting our communities from immigration agents using racial profiling and other illegal tactics when conducting their cruel and aggressive enforcement raids and sweeps will remain in place for now," she said in a statement.
Mohammad Tajsar, senior staff lawyer at the ACLU Foundation of Southern California, also welcomed the ruling.
"This decision is further confirmation that the administration's paramilitary invasion of Los Angeles violated the Constitution and caused irreparable injury across the region," he said in a statement.