Al-Munajjid was born in Riyadh, Saudi Arabia in 1960. He was raised in and currently lives in Saudi Arabia. He graduated from King Fahd University of Petroleum and Minerals (KFUPM) in Dhahran, Saudi Arabia, with a Bachelor's degree in Industrial Management.
In 1996, Al-Munajjid launched a question and answer Islamic website, IslamQA. IslamQA.com was banned in Saudi Arabia due to the fact that it was issuing independent fatwas. In Saudi Arabia, the kingdom's Council of Senior Scholars has sole responsibility and authority for issuing fatwas. The Council was granted this sole authority to issue fatwas by a royal edict issued in August 2010 (while restrictions had been in place since 2005, they were seldom enforced); this move was described by Christopher Boucek as "the latest example of how the state is working to assert its primacy over the country’s religious establishment."
On the cause of the 2004 Indian Ocean earthquake and tsunami: "The problem is that the [Christian] holidays are accompanied by forbidden things, by immorality, abomination, adultery, alcohol, drunken dancing, and … and revelry. A belly dancer costs 2500 pounds per minute and a singer costs 50,000 pounds per hour, and they hop from one hotel to another from night to dawn. Then he spends the entire night defying Allah. "Haven't they learned the lesson from what Allah wreaked upon the coast of Asia, during the celebration of these forbidden? At the height of immorality, Allah took vengeance on these criminals. "Those celebrating spent what they call 'New Year's Eve' in vacation resorts, pubs, and hotels. Allah struck them with an earthquake. He finished off the Richter scale. All nine levels gone. Tens of thousands dead. "It was said that they were tourists on New Year's vacation who went to the crowded coral islands for the holiday period, and then they were struck by this earthquake, caused by the Almighty Lord of the worlds. He showed them His wrath and His strength. He showed them His vengeance. Is there anyone learning the lesson? Is it impossible that we will be struck like them? Why do we go their way? Why do we want to be like them, with their holidays, their forbidden things, and their heresy?"
In a video posted on the Internet in January 2011 (as translated by MEMRI), Al-Munajjid issued a Fatwa to allow hacking to "Jewish Websites". Al-Munajjid stated that "In principle, hacking into websites and sabotaging them is forbidden. This is not allowed because Allah has forbidden spying" but explained, regarding "Jewish Websites," that:
"This is a special case that requires a special answer. The people whose property and websites are protected do not include criminal aggressors. These Jews are bombing from land, air, and sea, perpetrating a genocide against our brothers, killing women and children, and destroying homes and mosques with people inside... There is no doubt that they are criminals, corrupters, attackers, and saboteurs. Their websites are targeted in the context of the war against them.