Martin Luther King Jr. made significant contributions to the civil rights movement through his advocacy of nonviolence and peaceful protest. He organized and led several pivotal events, including the Montgomery Bus Boycott and the March on Washington, where he delivered his iconic "I Have a Dream" speech. King emphasized the importance of equality and justice through his philosophy of satyagraha. His leadership catalyzed significant legislative changes, including the passage of the Civil Rights Act of 1964 and the Voting Rights Act of 1965, leaving a profound legacy in the struggle for social justice in America.