Mozaffar ad-Din Shah Qajar (Persian: , romanized: Mozaffar ad-Din h-e Qjr; 23 March 1853 3 January 1907), was the fifth shah of Qajar Iran, reigning from 1896 until his death in 1907. He is often credited with the creation of the Persian Constitution of 1906, which he approved of as one of his final actions as Shah.

The Persian Constitutional Revolution (Persian: مشروطیت, romanized: Mashrūtiyyat, or انقلاب مشروطه Enghelāb-e Mashrūteh), also known as the Constitutional Revolution of Iran, took place between 1905 and 1911. The revolution led to the establishment of a parliament in Persia (Iran) during the Qajar dynasty.The revolution opened the way for fundamental change in Persia, heralding the modern era. It was a period of unprecedented debate in a burgeoning press, and new economic opportunities. Many groups fought to shape the course of the revolution, and all segments of society were in some way changed by it. The old order, which King Nassereddin Shah Qajar had struggled for so long to sustain, was finally replaced by new institutions, new forms of expression, and a new social and political order.

King Mozaffar ad-Din Shah Qajar signed the 1906 constitution shortly before his death. He was succeeded by Mohammad Ali Shah, who abolished the constitution and bombarded the parliament in 1908 with Russian and British support. This led to another pro-constitutional movement. The constitutionalist forces marched to Tehran, forced Muhammad Ali Shah's abdication in favor of his young son Ahmad Shah Qajar, and re-established the constitution in 1909.

The 1921 Persian coup d'état (Persian: کودتای ۳ اسفند ۱۲۹۹) refers to several major events which led to the establishment of the Pahlavi dynasty as Iran's ruling house in 1925. Iran's parliament amended the 1906–1907 constitution on December 12, 1925, replacing the 1797–1925 Qajar dynasty with the Pahlavi dynasty as the legitimate sovereigns of Iran. The revolution was followed by the Jungle Movement of Gilan (1914-1921).