The 2009 G20 London summit protests occurred in the days around the 2 April 2009 G20 London summit. The summit was the focus of protests from a number of groups over various long-standing and topical issues. These ranged from disquiet over economic policy, anger at the banking system and bankers' remuneration and bonuses, the continued war on terror and concerns over climate change.

The 2009 G20 London Summit was the second meeting of the G20 heads of government/heads of state, which was held in London on 2 April 2009 at the ExCeL Exhibition Centre to discuss financial markets and the world economy. It followed the first G20 Leaders Summit on Financial Markets and the World Economy, which was held in Washington, D.C., on 14–15 November 2008. Heads of government or heads of state from the G20 attended, with some regional and international organisations also represented. Due to the extended membership, it has been referred to as the London Summit.