The court heard the men wanted to kill a large number of people in revenge for the paper's publication of cartoons depicting the Prophet Muhammad in 2005.
The four were all Muslims resident in Sweden. Police said they were arrested just hours before the foiled attack.
The men, who had denied charges of terrorism, face up to 16 years in jail.
Jyllands-Posten's publication of the cartoons of Muhammad sparked protests in Muslim countries.
Munir Awad, Omar Abdallah Aboelazm and Munir Ben Mohamed Dhahri, a Tunisian citizen, were picked up by police on 29 December 2010 at a flat near Copenhagen.
Sabhi Ben Mohamed Zalouti was arrested a day later after crossing into Sweden, then extradited back to Denmark.