More than 150,000 people registered in a day to get the vaccine, a day after the kingdom received its first shipment.
Saudi Arabia has launched its coronavirus vaccination campaign, the Ministry of Health said, a day after it received two shipments of the Pfizer-BioNTech vaccine.
Shortly after that, Minister of Health Tawfiq al-Rabiah received the vaccine.
Saudi Arabia received its first two shipments on Wednesday, becoming the first country in the Middle East to obtain the vaccine developed by US pharmaceutical giant Pfizer and German partner BioNTech. It approved the use of the vaccine last week.
Saudi Arabian authorities asked people to register to be vaccinated via a mobile application; more than 150,000 people registered in 24 hours.
Citizens aged 65 and above, professionals at higher risks of COVID-19 exposure, as well as people with immune deficiency and chronic disease will be first recipients of the vaccine.
The second round will see people aged over 50, health practitioners and those with specific chronic diseases such as asthma and diabetes vaccinated.
The rest of the population will get the vaccine at the third stage, according to the health ministry.
Saudi Arabia, which has a population of some 34 million, has recorded more than 360,000 coronavirus cases, including 6,000 deaths.
Earlier this month, the United Arab Emirates launched a vaccination programme using another vaccine, Sinovac, after conducting trials with Chinese company Sinopharm.