How did the Iranian Revolution end the Pahlavi dynasty?

The Pahlavi dynasty effectively ended in early 1979 as a result of escalating civil unrest and the collapse of the shah’s political authority.

The process unfolded through several key developments:

• Escalating Protests: Throughout 1978, a cycle of violence between government forces and protesters—fueled by economic dissatisfaction, political repression, and opposition to the shah’s Westernization policies—eroded the regime's stability.123
• Departure of the Shah: On January 16, 1979, Mohammad Reza Pahlavi and his family fled Iran, officially characterizing the departure as a vacation. Although he never formally abdicated, his departure left a power vacuum that the Regency Council and Prime Minister Shahpur Bakhtiar could not fill.14
• Military Neutrality: The final collapse of the regime occurred on February 11, 1979, when Iran’s armed forces declared their neutrality, effectively ousting the remaining government.1
• Establishment of the Republic: Following the shah's flight, Ayatollah Ruhollah Khomeini assumed control. A national referendum held in his absence resulted in the official declaration of an Islamic republic on April 1, 1979.45