The overall law will still take effect Thursday, but without the provisions that angered opponents - including sections that required officers to check a person's immigration status while enforcing other laws.
The judge also put on hold parts of the law that required immigrants to carry their papers at all times, and made it illegal for undocumented workers to solicit employment in public places.
U.S. District Judge Susan Bolton ruled that the controversial sections should be put on hold until the courts resolve the issues.
The ruling came just as police were making last-minute preparations to begin enforcement of the law at 12:01 a.m. Thursday and protesters were planning a large demonstrations to speak out against the measure. At least one group planned to block access to federal offices, daring officers to ask them their immigration status.
The volume of the protests will be likely be turned down a few notches because of the ruling by Bolton, a Clinton appointee who suddenly became a crucial figure in the immigration debate when she was assigned the seven lawsuits filed against the Arizona law.
Lawyers for the state contend the law was a constitutionally sound attempt by Arizona - the busiest illegal gateway into the country - to assist federal immigration agents and lessen border woes such as the heavy costs for educating, jailing and providing health care for illegal immigrants.
The opponents argued the law will lead to racial profiling, conflict with federal immigration law and distract local police from fighting more serious crimes. The U.S. Justice Department, civil rights groups and a Phoenix police officer had asked the judge for an injunction to prevent the law from being enforced.
"There is a substantial likelihood that officers will wrongfully arrest legal resident aliens under the new (law)," Bolton ruled. "By enforcing this statute, Arizona would impose a 'distinct, unusual and extraordinary' burden on legal resident aliens that only the federal government has the authority to impose."
The law was signed by Republican Gov. Jan Brewer in April and immediately revived the national debate on immigration, making it a hot-button issue in the midterm elections.
The law has inspired rallies in Arizona and elsewhere by advocates on both sides of the immigration debate. Some opponents have advocated a tourism boycott of Arizona.
It also led an unknown number of illegal immigrants to leave Arizona for other American states or their home countries.
Federal authorities who are trying to overturn the law have argued that letting the Arizona law stand would create a patchwork of immigration laws nationwide that would needlessly complicate the foreign relations of the United States. Federal lawyers said the law is disrupting U.S. relations with Mexico and other countries and would burden the agency that responds to immigration-status inquiries.
Brewer's lawyers said Arizona shouldn't have to suffer from America's broken immigration system when it has 15,000 police officers who can arrest illegal immigrants.