The region's right-wing leadership approved regulations, which became known as “anti-mosque” laws, in January 2015, but Prime Minister Matteo Renzi later referred the new rules to the Constitutional Court for review.
Roberto Maroni, the Northern League president of the Lombardy region, took to Twitter on Wednesday to announce the court's decision, adding that left-wing politicians were hailing it “Allah”.
“The court has rejected our law regulating the construction of new mosques," Maroni wrote. "The left celebrates: Allah Akbar.”
La Consulta ha bocciato la nostra legge che regolamentava la costruzione di nuove moschee. La sinistra esulta: Allah Akbar- Roberto Maroni (@RobertoMaroni_) February 24, 2016
The region had sought to subject anyone wanting to build a mosque, or other place of worship for a faith not officially recognized by the state, to an exhaustive list of restrictions, effectively preventing any new construction.
Islam is the only major religion that does not have official status in Italy, despite the country being home to an estimated one million Muslims.
The court ruling falls in line with a government bid to better integrate the Muslim community and follows the announcement in January that a special council, made up of academics and experts in Islamic culture and religion, would be tasked with the job.